This post may contain affiliate links. Please read our disclosure policy.
I tested this chocolate zucchini cake four times to perfect the structure, lift, and rich chocolate flavor. With the right balance of eggs, cocoa, and leavening, plus a trick for handling the zucchini’s moisture, this cake turns out moist, fluffy, and deeply chocolatey every time.
Zucchini Chocolate Cake
This chocolate zucchini cake didn’t come together by luck. I tested it four times to get the texture, structure, and flavor exactly right.
The first version was based on my go-to chocolate cake, with shredded zucchini and a little oil added for moisture. It baked up with a strange texture—dense, spongy, and not the rich, tender crumb I was after.
Test two had the same texture issues, but the flavor was even worse. It was gross, I spit it out, and here’s the proof on Instagram.
I realized the zucchini and the oil/butter ratio was throwing off the balance, so I went back to the basics of structure and lift. In test three, I added a third egg for stability, blotted the zucchini to remove excess moisture, bumped up the cocoa powder for deeper flavor, and reworked the leavening.
The result was a major improvement—light, moist, and chocolatey—but the flavor still had a tinny aftertaste, which pointed to too much baking soda.
For the final round, I reduced the baking soda and brought in a bit of baking powder. That small change made all the difference. The finished cake is ultra moist yet fluffy, with rich chocolate flavor and no bitterness. The zucchini completely disappears (not literally) into the cake, adding moisture without leaving a trace.
I share this process so home bakers can feel confident knowing the recipe has been thoroughly tested and thoughtfully developed. If you’ve ever had a disappointing chocolate zucchini cake, this is the one that will change your mind. It’s reliable, flavorful, and easy enough for anyone to bake with success.
Why This Chocolate Zucchini Cake Works
This isn’t just another chocolate cake with veggies thrown in. Every detail in this recipe has been tested and refined to give you the best results.
- Extra egg for structure: Zucchini adds moisture, but it can also weigh the batter down. An extra egg strengthens the structure so the cake bakes up tall and fluffy.
- Balanced leavening: Too much baking soda can make the cake taste metallic. I use a mix of baking soda and baking powder to give the cake the perfect lift without any bitterness.
- Blotting the zucchini: Zucchini holds a lot of water. By blotting it before adding it to the batter, you get all the moisture benefits without ending up with a soggy or dense cake.
- More cocoa for deep flavor: Upping the cocoa powder gives the cake a rich, chocolate-forward flavor that stands out even with the added moisture from the zucchini.
These small adjustments make a huge difference. The end result is a moist, tender, chocolate-packed cake that hides the zucchini so well, even picky eaters won’t know it’s there.
Pro Tips for the Best Chocolate Zucchini Cake
- Blot your zucchini. After shredding, use paper towels to blot excess moisture. You want it damp, not dripping. This prevents a soggy or gummy cake texture.
- Use a mix of leaveners. Baking soda helps neutralize acidity from the cocoa and buttermilk, but too much can cause a bitter or metallic flavor. A combination of baking soda and baking powder gives better lift and balanced taste.
- Add the zucchini last. Stir it in gently after the batter is mixed. This keeps the texture light and ensures the zucchini is evenly distributed without overmixing the batter.
How to Make Chocolate Zucchini Cake
This chocolate zucchini cake recipe is the perfect way to use up an abundance of zucchini, or to sneak something healthy in to a delicious cake. Follow my simple step-by-step guide:
For the Cake
- Prep oven and pans. Preheat the oven to 350°F (177°C). Lightly grease two or three 8-inch or 9-inch round cake pans and line the bottoms with parchment paper for easy removal.
- Prep zucchini. Shred the zucchini using the standard side of a box grater. Measure out 3 cups (roughly 360g), then spread the shredded zucchini onto a few layers of paper towels. Gently blot to remove excess moisture, but do not squeeze dry.
- Combine dry ingredients. In a large mixing bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt. Set aside.
- Combine wet ingredients. In a separate large bowl, combine the melted butter, oil, granulated sugar, brown sugar, eggs, and vanilla extract. Mix until smooth and well combined.
- Combine wet and dry ingredients. Gradually add half of the dry ingredients to the wet mixture and mix until mostly combined. Add half of the buttermilk and stir. Repeat with the remaining dry ingredients, then the remaining buttermilk and the hot tap water. Mix until the batter is smooth, but do not overmix.
- Mix in zucchini. Gently stir the blotted shredded zucchini into the batter until evenly distributed.
- Transfer batter. Divide the batter evenly between the prepared pans. If using 2 pans, add about 3¼ cups of batter per pan. If using 3 pans, add a little over 2 cups per pan.
- Bake. Bake 2 pans for 30 to 40 minutes, or 3 pans for 25 to 35 minutes, or until a toothpick inserted in the center comes out with moist crumbs.
- Cool. Allow the cakes to cool in the pans for 20-30 minutes, then run a knife around the edges and turn them out onto wire racks to cool completely before frosting.
For the Chocolate Frosting
- Beat butter. In a mixing bowl, beat the butter on high for 3 minutes.
- Mix in dry ingredients. Sift in the cocoa powder and 3 cups of powdered sugar. I like to sift these in because it helps break up clumps, creating a light and fluffy frosting. Beat the frosting on low speed until combined and thick.
- Add remaining ingredients. Mix in 3 tbsp of heavy cream, vanilla extract and salt.
- Mix in remaining powdered sugar and adjust as needed. Add in the additional powdered sugar (1-2 cups), mix on low. If the frosting is too thick, beat in an additional tablespoon of heavy cream.
Assemble
- Level cakes and assemble layers. If needed, level the cooled cakes using a cake levered or serrated knife. Spread a small amount of chocolate buttercream on the bottom of your cake plate / stand, this acts as “glue” to prevent the cake from moving. Place one cake layer over the frosting. Measure 3/4 to 1 cup of frosting and evenly spread that on top of the first layer. Top with the second cake layer and spread the remaining frosting around the sides and top of the cake. I use about 1 cup of frosting on the top of the cake.
- Slice and serve. Cover leftover cake tightly with plastic wrap and store on the counter for up to 3 days.
Chocolate Zucchini Cake Storage
Store any leftover cake wrapped tightly or in an airtight container at room temperature for 2 days or refrigerated for up to 5 days.
Freezing Chocolate Zucchini Cake
You can also freeze chocolate zucchini cake. First, allow both the cake and frosting to cool completely. Freezing while still warm can cause condensation, which may lead to a soggy texture.
You can freeze the entire cake or individual slices. If freezing the whole cake, leave it on a sturdy cake board or baking sheet for support. For individual portions, slice the cake as you normally would for serving.
Wrap each slice (or the whole cake) tightly in plastic wrap, then add a layer of aluminum foil for extra protection. You can also place the wrapped slices in a freezer-safe container or a zip-top freezer bag. Be sure to label it with the date, and freeze for up to 2–3 months for the best flavor and texture.
To thaw, remove the cake from the freezer, unwrap it, and let it sit at room temperature until completely defrosted. If thawing in a container, keep it loosely covered to prevent it from drying out.
More Dessert Zucchini Recipes
Tap stars to rate!
Chocolate Zucchini Cake
Ingredients
Cake
- 2 ½ cups (300g) all-purpose flour
- ¾ cup (63g) natural unsweetened cocoa powder
- 1 tsp baking soda
- 1 tsp baking powder
- 1 tsp salt
- ½ cup (113g) unsalted butter, melted
- ½ cup (118ml) vegetable oil
- 1 cup (198g) granulated sugar
- 1 cup (213g) brown sugar
- 3 large eggs
- 1 tsp vanilla extract
- 1 cup (236ml) buttermilk
- ½ cup (118ml) hot tap water
- 3 cups (360g) shredded zucchini, blotted
Chocolate Frosting
- 2 cups (452g) unsalted butter, room temperature
- 1 cup (84g) unsweetened natural cocoa powder
- 4-5 cups (454-567g) powdered sugar
- 3-4 Tbsp heavy cream
- ¼ tsp salt
- 1 tsp vanilla extract
Instructions
Cake
- Preheat the oven to 350°F (177°C). Lightly grease two or three 8-inch or 9-inch round cake pans and line the bottoms with parchment paper for easy removal.
- Shred the zucchini using the standard side of a box grater. Measure out 3 cups (roughly 360g), then spread the shredded zucchini onto a few layers of paper towels. Gently blot to remove excess moisture, but do not squeeze dry.
- In a large mixing bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt. Set aside.2 ½ cups (300g) all-purpose flour, 3/4 cup (63g) natural unsweetened cocoa powder, 1 tsp baking soda, 1 tsp baking powder, 1 tsp salt
- In a separate large bowl, combine the melted butter, oil, granulated sugar, brown sugar, eggs, and vanilla extract. Mix until smooth and well combined.½ cup (113g) unsalted butter, ½ cup (118ml) vegetable oil, 1 cup (198g) granulated sugar, 1 cup (213g) brown sugar, 3 large eggs, 1 tsp vanilla extract
- Gradually add half of the dry ingredients to the wet mixture and mix until mostly combined. Add half of the buttermilk and stir. Repeat with the remaining dry ingredients, then the remaining buttermilk and the hot tap water. Mix until the batter is smooth, but do not overmix.1 cup (236ml) buttermilk, ½ cup (118ml) hot tap water
- Gently stir the blotted shredded zucchini into the batter until evenly distributed.3 cups (360g) shredded zucchini
- Divide the batter evenly between the prepared pans. If using 2 pans, add about 3¼ cups of batter per pan. If using 3 pans, add a little over 2 cups per pan.
- Bake 2 pans for 30 to 40 minutes, or 3 pans for 25 to 35 minutes, or until a toothpick inserted in the center comes out with moist crumbs.
- Allow the cakes to cool in the pans for 20-30 minutes, then run a knife around the edges and turn them out onto wire racks to cool completely before frosting.
Chocolate Frosting
- In a mixing bowl, beat the butter on high for 3 minutes.2 cups (452g) unsalted butter
- Sift in the cocoa powder and 3 cups of powdered sugar. I like to sift these in because it helps break up clumps, creating a light and fluffy frosting. Beat the frosting on low speed until combined and thick.1 cup (84g) unsweetened natural cocoa powder, 4-5 cups (454-567g) powdered sugar
- Mix in 3 tbsp of heavy cream, vanilla extract and salt.3-4 Tbsp heavy cream, ¼ tsp salt, 1 tsp vanilla extract
- Add in the additional powdered sugar (1-2 cups), mix on low. If the frosting is too thick, beat in an additional tablespoon of heavy cream.
Assemble
- If needed, level the cooled cakes using a cake levered or serrated knife. Spread a small amount of chocolate buttercream on the bottom of your cake plate / stand, this acts as “glue” to prevent the cake from moving. Place one cake layer over the frosting. Measure 3/4 to 1 cup of frosting and evenly spread that on top of the first layer. Top with the second cake layer and spread the remaining frosting around the sides and top of the cake. I use about 1 cup of frosting on the top of the cake.
- Slice and serve. Cover leftover cake tightly with plastic wrap and store on the counter for up to 3 days.
