The secret to moist, irresistible chocolate cake? Add zucchini! Chocolate zucchini cake is made with two layers of rich chocolate cake that's topped with fluffy chocolate buttercream frosting.
Recipe summary
Flavor/texture: Moist and tender with rich, chocolate flavor. No one would ever guess there's zucchini inside!
Pan size: Two 8-inch or 9-inch round pans
Serves: 16 or more people
Make cupcakes instead: Chocolate Zucchini Cupcakes
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Ingredients and substitutions
- Zucchini - You'll need about 2 cups or 300 grams of zucchini for this recipe.
- Wet ingredients - Oil, granulated sugar, eggs, and vanilla add moisture and flavor to your cake. Reducing or omitting these ingredients can result in a dry cake.
- Dry ingredients - All-purpose flour, natural cocoa powder, baking powder, baking soda, and salt balance with the wet ingredients and add structure and lift. If you have a different type of flour on hand, search for a recipe developed with that flour in mind (making untested substitutions can result in wasted ingredients).
- Frosting ingredients - Butter, heavy cream, confectioner's sugar, cocoa powder, vanilla, and salt create a simple chocolate buttercream frosting.
How to make chocolate zucchini cake
- Add wet ingredients to a large bowl and mix to combine.
- Whisk dry ingredients in a separate bowl, then add to wet ingredients and stir to combine.
- Divide batter between two cake pans. Use a kitchen scale for even cake layers.
- Bake until cake reaches 210F in the center and the middle pops back when gently pressed. Cake will begin to pull away from the sides when it's done.
- While your cake cools, prepare the frosting with a hand mixer in a large bowl.
- Flip cakes out of the pans and trim the rounded tops with a serrated knife. Place one cake, cut side down, on a serving plate and top with a layer of frosting.
- Place second cake layer, cut side down, on top of the frosting layer.
- Top with another layer of frosting on top, and use the remaining frosting to cover the sides. Use an offset spatula for best results.
Heather's Top Tip
Use an instant-read thermometer to test the doneness of your cakes and cupcakes. Cake is done when it reaches 210F in the center. This ensures your cake is perfectly baked, not undercooked or dry.
Tips and tricks
Use finely grated zucchini - Use the small side of a box grater. A larger grate can leave a bit of texture in your cake after baking, while finely grated zucchini melts right into the batter.
Do not squeeze the liquid from your zucchini - We're utilizing that liquid to thin the cake batter and add moisture. Otherwise, the batter will turn out too thick to rise properly.
Use natural cocoa powder - This recipe is made with natural cocoa powder. The amount of baking soda and baking powder is balanced with its acidity to help the cake rise properly. If you use Dutch cocoa, your cake will rise less in the oven, and have a milder flavor and darker color.
Do not frost a warm cake - The frosting will melt if your cake is still warm. Allow your cakes to cool completely before frosting and serving.
Frequently asked questions
No. Buttercream frosting is popular because it's no-cook and made with two main ingredients: confectioner's sugar and butter. By reducing the sugar, you're essentially making a lightly sweetened butter, which doesn't make for a great frosting. Instead, opt for a less-sweet frosting like whipped cream or ermine frosting.
No, this cake does not need to be refrigerated, unless your home is reaching 90F. Buttercream frosting will begin to melt and weep if it reaches this temperature. If your home is hot or you'd like to display your cake outdoors in the summer, keep it refrigerated until about 30 minutes before serving and display it in the shade.
Yes, chocolate zucchini cake freezes well for up to 3 months. Place cake in the freezer, uncovered, until solid (about 2-3 hours). Gently wrap in plastic wrap and foil while frozen, then return to the freezer. To thaw, unwrap and place at room temperature, uncovered, for 2-3 hours to bring back to room temperature before serving.
It tastes just like any other rich chocolate cake. Zucchini has a mild flavor that's undetectable in baked goods and only adds a moist, tender texture to the baked cake.
Zucchini replaces the milk or buttermilk component commonly found in chocolate cake recipes.
Yes. This amount of batter works great in a 9x13 pan or 13x18 half-sheet pan.
9x13 pan - About 32-38 minutes
13x18 pan - About 18-20 minutes
As always, use visual cues to determine whether your cake is done instead of relying on time alone.
📖 Recipe
Chocolate Zucchini Cake
Ingredients
Cake
- 2 cups (300 g) finely grated zucchini, do not drain liquid out
- 1 ¾ cups (345 g) granulated sugar
- ¾ cup (150 g) vegetable oil
- 3 large eggs, room temperature
- 2 teaspoons vanilla extract
- 2 cups (240 g) all-purpose flour
- ¾ cup (63 g) natural cocoa powder
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
Frosting
- 1 cup (227 g) unsalted butter, room temperature
- 3 cups (342 g) confectioner's sugar
- ½ cup (40 g) natural cocoa powder
- ⅓ cup (76 g) heavy cream, cold
- ⅛ teaspoon salt
- 2 teaspoons vanilla extract
Instructions
Cake
- Preheat oven to 350℉. Grease two 8-inch or 9-inch round cake pans, line the bottoms with parchment circles, and set aside.
- In a large bowl, add finely grated zucchini (including any excess liquid), granulated sugar, oil, eggs, and vanilla extract. Stir until evenly combined.
- In a separate bowl, whisk together dry ingredients: flour, cocoa powder, baking soda, baking powder, and salt. Add to wet ingredients and stir until just combined.
- Pour batter evenly between your two prepared round cake pans. Gently tap on the countertop to remove air bubbles.
- Two 9 inch round cake pans: 26-30 minutesTwo 8 inch round cake pans: 28-34 minutesBake your cake using the time frames above as a reference.
- To test for doneness: Is your cake jiggly in the center? It needs more time. If it's not jiggly, gently press the top of the cake. If an indent is left, it needs more time. if it pops back, the cake is done. Cake temperature can also be tested with an instant-read thermometer. It's done when it reaches 210F in the center.
- Remove cake from oven and allow to cool completely in the pan(s) on a wire cooling rack.
Frosting
- Meanwhile, in a large bowl, add butter. Using a hand mixer or stand mixer, beat until fluffy, about a minute.
- Add confectioner's sugar and cocoa powder, half at a time, and slowly mix until ingredients are incorporated. Then, whip at high speed for 1 to 2 minutes, or until light and fluffy.
- Add heavy cream, salt, and vanilla extract and whip an addition 1 to 2 minutes, or until light and fluffy.
- Gently flip and remove cooled cakes from their pans. Trim the rounded tops with a serrated knife to make flat layers.
- Place one layer, top side down, onto a cake stand or serving plate. Top with frosting and spread into an even layer. Add second layer of cake, top side down, and top with another layer of frosting. Spread remaining frosting onto the sides of the cake.
Recommended Equipment
Notes
- Nutrition: estimate is calculated for 16 slices of cake.
- To make a single layer sheet cake: this recipe can be baked in a 9x13 baking pan for about 32-38 minutes, or a 13x18 half sheet pan for about 18-20 minutes.
- Frosting: Recipe makes enough frosting to thinly coat the middle, top, and sides as shown in the photos.
- Want a less sweet frosting? Try an ermine frosting or whipped cream instead. Reducing the sugar in buttercream results in a greasy, lightly-sweetened butter rather than a frosting.
- Storage: Homemade cake is best served the same day for best moisture and texture. Leftovers will keep for 2-3 days at room temperature, 3-4 days in the refrigerator, or up to 3 months in the freezer. Refrigerated cake needs to come to room temperature for 1 hour before serving, and frozen cake needs 2-3 hours to come to room temperature before serving.
I had so much fun creating this recipe! I hope you give it a try and love it as much as I do. If you have a question, check out the post above, which is packed with information about the recipe. Tried the recipe? I'd love to hear your thoughts — leave a comment and a star rating to share your feedback!