Super moist and indulgent chocolate zucchini cake is studded with chocolate chips and topped with chocolate fudge frosting. Made with 3 cups of shredded zucchini (you can’t taste it!), this is the most decadent way to eat your greens.
I originally published this recipe in 2017 and have since added new photos, a video tutorial, and additional success tips.
Today, we have a triple dose of chocolate in the form of luxuriously rich chocolate zucchini cake. No, you can’t taste the zucchini. No, you can’t see the zucchini. Yes, it’s unbelievably delicious and I’m showing you exactly how to make it! Zucchini recipes have never been more decadent than this one. 🙂
Can you just look at how rich and moist this cake is? It tastes even better than it looks, I swear. The real secret behind it is the hidden vegetable inside. If you’re one who believes these veggies should only be in zucchini casserole, zucchini fritters, or zucchini biscuits and have nothing to do with dessert, keep an open mind. Carrot cake, anyone?!
Why You’ll Love This Chocolate Zucchini Cake
- Just as loved as my chocolate cake
- Super moist and rich with mega chocolate flavor
- Easy to make
- A delicious way to use up a bumper crop of summer zucchini
- 3 cups of vegetables hiding inside—and you don’t even taste it
- Covered in fudge-like chocolate buttercream
One reader, Stacie, commented: “Delicious chocolate cake! No evidence of three cups of zucchini in there! So good!!! ★★★★★“
One reader, Emily, commented: “This was amazing! Probably the best chocolate cake we’ve ever had—so moist! And no one even guessed there was zucchini in it. ★★★★★“
One reader, Kara, commented: “This wasn’t just the best zucchini recipe I’ve ever tried, it was the best cake recipe as well! The zucchini here makes this moist and fudgy, almost like a brownie, but still fluffy like cake. I used cream cheese frosting and it was divine. I will be making this for birthdays in the future! ★★★★★“
Overview: Chocolate Zucchini Cake Ingredients
This decadent cake is made with fresh zucchini and pantry basics. Did you know that cocoa powder can dry out baked goods much more than flour? To compensate for this, we ensure there’s plenty of added moisture in the cake batter.
Let’s review a few key ingredients:
- Unsweetened Natural Cocoa Powder: Cocoa powder takes the place of some flour. Just as in my regular chocolate cake recipe, make sure you’re using natural unsweetened cocoa powder instead of Dutch-process cocoa powder.
- Espresso Powder: Espresso powder accentuates the chocolate flavor. While optional, I highly recommend using it. The chocolate zucchini cake won’t taste like coffee. Rather, the espresso powder helps bring out the intense chocolate flavor. We use it in chocolate zucchini bread and in this chocolate cake roll, too. You can find espresso powder in the coffee aisle at the grocery store or online.
- Oil: Oil adds moisture. You can try replacing *some* of the oil with unsweetened applesauce. I’ve done this with chocolate cakes and muffins and the result is wonderful, but I don’t recommend replacing all of it. Despite the zucchini inside, this isn’t health food, it’s dessert. Don’t try to make it into something it’s not!
- Eggs: 4 eggs bind everything together and add moisture. Remember that room-temperature ingredients are important.
- Sour Cream: Just like in chocolate peanut butter cake, you can use sour cream or plain yogurt. Either add moisture.
- Zucchini: Use a whopping 3 cups of shredded zucchini in this recipe. Testing how much we can get away with… without actually tasting it! Zucchini is pure magic in cakes—nothing but flavorless moisture. Same goes with my zucchini bread, apple zucchini bread, and zucchini muffins, too!
Optional Chocolate Chips: For mega chocolate flavor, add chocolate chips to the batter. They’re key to those melty pockets of chocolate in each slice. I use semi-sweet chocolate chips (just like in my peanut butter chocolate chip zucchini bread), but mini chocolate chips or even dark chocolate chips pair wonderfully, too.
Let Me Show You How to Make It:
This chocolate zucchini cake comes together quickly and easily, just like my regular zucchini cake. Simply whisk the dry ingredients in one bowl and beat the wet ingredients together in another bowl. Combine the wet and dry ingredients, then add the chocolate chips. The cake batter will be slightly thick thanks to all of the zucchini! Divide the batter between two 9-inch cake pans; or you can make a quarter sheet cake using a 9×13-inch cake pan. See the recipe Notes section for details.
- Need cupcakes instead? This recipe yields about 24–30 cupcakes. See recipe Notes.
Chocolate Frosting
We’re topping and filling this chocolate zucchini cake with smooth, silky, and creamy chocolate buttercream. You’ll use my favorite chocolate buttercream recipe, but increase the quantity as directed in the recipe card below.
How to Assemble a Layer Cake
If you’re new to assembling and layering cakes, or if you just need a refresher, see my How to Assemble a Layer Cake video tutorial. The quick video guide will walk you through how to stack and decorate it.
If you would rather top this cake with vanilla frosting, use the vanilla frosting included in my white cake recipe. Regardless of which you choose, you’ll have enough frosting to frost the entire layer cake AND a little leftover for some fun piping on top. Decorate however you’d like! I used Wilton 1M for the pictured piping:
Deep, dark, luxuriously rich, crazy moist, and weirdly loaded with vegetables that you absolutely can’t taste. After one bite you’ll be convinced this is the best way to eat your veggies! You’ll love my zucchini oatmeal chocolate chip cookies, too.
More Chocolate Recipes
- Chocolate Lava Cakes
- Flourless Chocolate Cake
- Chocolate Cake
- Chocolate Cupcakes
- Homemade Brownies
- Inside Out Chocolate Chip Cookies & Double Chocolate Chip Cookies
Chocolate Zucchini Cake
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Total Time: 3 hours, 30 minutes
- Yield: serves 10-12
- Category: Dessert
- Method: Baking
- Cuisine: American
Description
This super rich and moist chocolate zucchini cake is topped with the best chocolate frosting—you won’t even taste the vegetables!
Ingredients
Cake
- 2 cups (250g) all-purpose flour (spooned & leveled)
- 3/4 cup (62g) unsweetened natural cocoa powder
- 2 teaspoons baking soda
- 1/2 teaspoon baking powder
- 1 teaspoon espresso powder (optional)
- 1/2 teaspoon salt
- 1 cup (240ml) canola or vegetable oil
- 1 cup (200g) granulated sugar
- 3/4 cup (150g) packed light or dark brown sugar
- 4 large eggs, at room temperature
- 1/3 cup (80g) sour cream or plain yogurt, at room temperature
- 2 teaspoons pure vanilla extract
- 3 cups (about 360g) shredded zucchini (lightly blotted; see recipe Note) (2 medium zucchini, about .75–1 lb.)
- 1 cup (180g) semi-sweet chocolate chips (regular or mini)
Chocolate Buttercream
- 1 and 1/4 cups (282g) unsalted butter, softened to room temperature
- 3 and 1/2 cups (420g) confectioners’ sugar
- 3/4 cup (62g) unsweetened cocoa powder (natural or Dutch-process)
- 3–5 Tablespoons (45–75ml) heavy cream (or half-and-half or whole milk), at room temperature
- 1/4 teaspoon salt
- 1 teaspoon pure vanilla extract
- optional for decoration: chocolate chips and/or chocolate sprinkles
Instructions
- Preheat oven to 350°F (177°C). Grease two 9-inch round cake pans, line with parchment paper rounds, then grease the parchment paper. Parchment paper helps the cakes seamlessly release from the pans. (If it’s helpful, see this parchment paper rounds for cakes video & post.)
- Make the cake: Whisk the flour, cocoa powder, baking soda, baking powder, espresso powder (if using), and salt together in a large bowl. In another large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the oil, granulated sugar, brown sugar, eggs, sour cream, and vanilla together until combined. Add the zucchini and mix to incorporate. Add the dry ingredients to the batter and beat on medium speed until completely combined. Fold in the chocolate chips. Batter will be slightly thick.
- Pour batter evenly into cake pans. Bake for around 28–32 minutes or until the cakes are baked through. To test for doneness, lightly poke the top of the cake with your finger—if it bounces back instead of leaving , the cake is done. Or you can insert a toothpick into the center of the cake—if it comes out clean, it’s done.
- Set the cakes on a cooling rack and let cool in the pans for 1 hour. After 1 hour, remove the cakes from the pans, discard the parchment rounds, and let the cakes finish cooling directly on the rack. The cakes must be completely cool before frosting and assembling.
- Make the buttercream: With a handheld or stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add confectioners’ sugar, cocoa powder, 3 Tablespoons of cream, salt, and vanilla. Beat on low speed for 30 seconds, then gradually increase to high speed and beat until it’s smooth and creamy. Do not over-whip. Add 1/4 cup more confectioners’ sugar or cocoa powder if frosting is too thin or 1–2 more Tablespoons of cream if frosting is too thick. (I usually add 1 more.) Taste. Add another pinch of salt if desired.
- Assemble and frost: First, using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Discard (or crumble over ice cream!). Place 1 cake layer on your cake stand, cake turntable, or serving plate. Evenly cover the top with a heaping cup of frosting. Top with 2nd cake layer and spread the remaining frosting all over the top and sides. Pipe any leftover frosting on top. (I used Wilton 1M tip.) Decorate with chocolate sprinkles or chocolate chips if desired. Slice and serve.
- Cover leftover cake and store at room temperature for up to 2 days or in the refrigerator for up to 5 days.
Notes
- Make Ahead Instructions: Prepare cakes and frosting 1 day in advance. Keep cakes at room temperature, covered tightly. Refrigerate prepared frosting in an airtight container, then bring to room temperature when ready to use. Frosted or unfrosted cakes may be frozen up to 2 months, thaw overnight in the refrigerator and bring to room temperature, if desired, before serving.
- Special Tools (affiliate links): Box Grater | Glass Mixing Bowls | Electric Mixer (Handheld or Stand) | 9-inch Round Cake Pan | Cake Turntable | Wilton 1M Piping Tip | Piping Bag (Reusable or Disposable) | Cake Carrier (for storage)
- Blot the Zucchini: Give the shredded zucchini a very light blotting with a towel. Don’t squeeze too much moisture out, just a little blot before adding to the wet ingredients. I own and love this box grater—works quickly!
- 9×13-inch Cake: Interested in making a sheet cake instead? This batter will fit into a 9×13-inch pan. The bake time is long—at least 45 minutes to ensure the thick cake is baked through. Same oven temperature.
- Non-Chocolate Zucchini Cake: Looking for zucchini cake without chocolate? Here is my regular zucchini cake topped with brown butter cream cheese frosting.
- Cupcakes: This recipe yields 24–30 cupcakes. Bake for 18–22 minutes or until a toothpick inserted in the center comes out *mostly* clean with no wet batter. Same oven temperature.
Instead of cake, try these as cupcakes! Directions in the recipe Notes above.
Reader Comments and Reviews
This was so good and I can’t believe how fast it disappeared. Ok I can, I have 2 teenaged boys but oh my. Good thing I have so much zucchini, I need to make it again very soon
Halved the recipe as I had a small amount of chocolate buttercream left over. Baked in a 8 inch square pan. Was the perfect thickness for 9 pieces. I will probably regret halving the recipe when I get up tomorrow and the kids have eaten it all again .
We declare this to be the best cake we’ve ever had, and I bake a lot, thanks to Sally… A few notes on subs: used 2 flax eggs and 2 large chicken eggs (I can’t do too much yolk), coconut milk yogurt (instead of dairy), and avocado oil (nutritional preference over canola or veggie oil). All worked great. Silicone bundt pan for 1 hour and 5 minutes.
I have made this many times in the US using natural coco which is readily available. Now I’m in Switzerland and the coco here is all Dutch processed.is there anyway tween the ratio of baking soda to powder so the PH level is accurate and it will rise properly? Eager to make this for my Swiss peeps..they love zucchini and chocolate here!!
Hi Kelly! Natural cocoa powder really is best here. Using Dutch process would require some tweaking of the leavening as you mention, but we haven’t tested anything ourselves. Let us know if you decide to do any experimenting!
We just made this cake last night using Dutch process cocoa, because that is all we had, and my husband loved it. We did a 9×13 and it rose beautifully. I am not sure if the flavor is different, as I have never made it before. We greased and floured the bottom and sides, and it came out easily.
My ALL TIME FAVORITE CAKE RECIPE!!! Thank you Sally.
I did struggle finding the recipe back. Using Safari as my web brower I could get the site to come up but it would not let me click into a recipe. Does Sally’s site now only work with Chrome?
Hi Michele, our website works on all browsers. Does your Safari need an update by chance? We haven’t heard of any other readers having this problem, but try updating your browser and letting us know if that helps. We’re so glad you enjoyed the cake!
I grow zucchinis hust for this recipe! So yummy, our favorite!
Family Favorite! I use this for my summer Birthday cakes when I have lots of garden zucchini. I do omit the coffee since it makes the grandkids a little too jazzed up!
This is an amazing dark moist cake. I made coconut frosting for it and covered it in unsweetned coconut flakes. Great!
Easy, excellent and moist. I made a Bundt cake with drizzled chocolate glaze. Passed the teen aged boys test!
Like most people making zucchini-based baked goods I made this cake to use up a glut of garden zucchini. But everyone who’s tried it says it’s the best cake they’ve ever had (not the best zucchini cake or the best chocolate cake but the best cake, period). So I may find myself buying zucchini mid-winter just to make this cake again! I baked it in a Bundt pan which took about an hour. I used extra virgin olive oil for richness, left out the chocolate chips, and made a cocoa drizzle with equal parts cocoa power and powdered sugar mixed with a little milk.
My go-to chocolate cake now!
Made this twice in the last week, first time I halved the recipe to make two small cakes and frosted them with whipped coffee buttercream, it was so good! The cake is so moist and light, like a chocolate muffin texture.
Just made it again today and going to make a thin chocolate icing for a lighter version.
Highly recommend this recipe
So glad you enjoy it. It’s one of my favorite bakes with zucchini!
a family fav!
Can you do a bunt cake instead with this recipe
Hi Sandy, We’re unsure of the exact bake time for a Bundt cake, but it will take well over the time needed for the cake layers. Keep a close eye on it and use a toothpick to test for doneness. Hope it’s a hit!
Just did this and it took around an hour. I’d start checking at 45 minutes.
What a great recipe! I made it yesterday, it came out exactly as described, it’s delicious, I used Dutch Cocoa and I didn’t used the coffee, it’s soft, moist and with a very deep chocolate flavor! Thanks for your recipe!
This is my second summer making this cake with my fresh zucchini. It’s the best chocolate cake I’ve ever made. I don’t change the recipe at all.
Best chocolate cake recipe that I’ve ever made! And I like how the measurements are given in grams as well as cups.
Where us the recipe for the icing
Hi Judy, we recommend using either our chocolate frosting or vanilla frosting recipes.
Hi Sally! Just a question. What did you add to your piped decoration frosting, as the rosettes are distinctively darker in color? Thanks so much!
Hi Terry! If I remember correctly, I think I added a little more cocoa powder and confectioners’ sugar to it to thicken it.
Thanks so much. I appreciate it, and all that you and your team do!
This cake is AWESOME!! Even my super picky husband likes it lol will most definitely be making this again this summer as the zucchini have already started rolling in☺️
Fantastic chocolate cake.
This cake is incredible!
Could you please adjust to a 9×9 pan recipe
Hi Denise, it shouldn’t be an issue to halve this recipe for a one layer 9 inch cake.
I love your recipes, but this list of recipes that people “saved the most” in May makes no sense. Zuchini isn’t in season yet in May. August or September, I’d believe it.
Hi O’Lady, your comment is incorrect. I had this recipe get a lot of traffic from YouTube and Facebook over the past 2 months, which brought up the # of saves significantly in May. Hope you try it later in the summer!
I used frozen shredded zucchini from my garden and you can make it year round
Hi, O’Lady. I shred and freeze my zucchini just for this recipe.
This was easy and absolutely phenomenal! I am not a huge fan of chocolate, but this was amazing. You can’t taste the zucchini at all, and the cake is incredibly moist. The chocolate buttercream frosting is delicious, as well!
This Chocolate Zucchini Cake is a delightful blend of rich chocolate and moist zucchini. Thank you for sharing such a fantastic recipe!
This is a good one! Very juicy – and i did squeeze the zucchini quite a lot! Substituted some butter for the oil as i ran out of oil lol
Not sure what cake flour is.
Do you use plain or self-raising?
Hi Emily, cake flour is extra fine and light. This recipe does not call for cake flour. You can read more about cake flour and making your own DIY version here!
Emily,
Plain flour does not have the baking powder, baking soda or salt in it. Self-rising flour does. So if the recipe calls for those ingredients then use plain flour.
Made this for my Mum’s 95th birthday. It was so lovely and everyone loved it. Even my fussy son!!
So glad to hear it!
Sadly didnt rise at all, not sure what i did wrong, flavour is good, just very dense and, well, not risen at all.. kept to the recipe super closely
Sometimes when cakes don’t rise, it’s a simple issue of your baking soda or baking powder being old. They can lose freshness after a few months!
I don’t bake very often, but I whip this recipe out for special occasions! I really appreciate all the tips and notes, it makes the recipe easy to follow and stress free even as a beginner with little baking knowledge 🙂
So glad you love this cake, Sam!
Hi there,
I’d like to make this recipe but wonder what I could substitute for the sour cream. I don’t do well with dairy, tho butter is fine (thank god)
Hi Kristy, yogurt is a fine substitute—perhaps you could try with a dairy-free yogurt? Let us know if you do!
I have made this cake for so many people’s birthdays. All I ever get is rave reviews. Thanks Sally. Please keep baking!
Hi Sally
I’ve often looked at your site and wanted to make your recipes. Finally found one I was game to try. Loved this super quick, easy & versatile cake. Did a half portion and baked it in a 7″ tin for 30 minutes at 180 degrees. It was still liquidy inside so increased it to 200 degrees for 10 minutes and it came out perfect! Also substituted ingredients I didn’t have
– sunflower oil instead of canola or vege oil
– 2 teaspoons of Moccona Indulgence (8) instead of espresso coffee and
– 75g white sugar and 50 g dark cane sugar.
Cake was beautifully moist. Did a chocolate fudge sauce icing made with milk, not cream which surprisingly worked and much less fattening.
Would love to know if the sugars can be substituted with rice malt syrup and what quantities, and if you could use other neutral tasting vege, such as peas, lettuce, spinach, broccoli, kale etc.
I look forward to your reply, and can’t wait to try more of your recipes.
By the way, thanks for the metric measurements too.
Hi Yallas! We have not tested sugar substitutes or other veggies in the cake, but would caution against altering the recipe too much as the results will vary. It may be best to find a recipe suited for those ingredients. Glad you enjoyed this recipe!