Chocolate zucchini cake takes the rich, deep flavor of a classic chocolate layer cake and makes it even more moist with the addition of grated zucchini. It’s frosted with a rich chocolate buttercream, making it a decadent dessert that happens to have a vegetable hiding in the batter — not that anyone would guess.
Why Zucchini Makes This Chocolate Cake Even Better
Grated zucchini blends completely into the batter as it bakes, adding moisture without any detectable vegetable flavor. Combined with cocoa powder, this results in an extra-moist chocolate cake with a soft, tender crumb — arguably better than a standard chocolate cake recipe.
Ingredients
For the cake
- 2 cups grated zucchini (about 1 large zucchini), excess moisture squeezed out
- 2 ½ cups all-purpose flour
- 1 cup unsweetened cocoa powder
- 1 ½ teaspoons baking soda
- ½ teaspoon baking powder
- 1 teaspoon salt
- 1 cup vegetable oil
- 1 ½ cups granulated sugar
- ½ cup packed brown sugar
- 3 large eggs
- 1 tablespoon vanilla extract
- ½ cup milk
For the chocolate frosting
- 1 cup unsalted butter, softened
- 1 ½ cups unsweetened cocoa powder
- 4 cups powdered sugar
- ½ cup milk or heavy cream
- 1 teaspoon vanilla extract
- Pinch of salt
Equipment
- A box grater
- Two 9-inch round cake pans
- Parchment paper
- Two mixing bowls
- A hand or stand mixer
- A wire rack
Instructions
Step 1: Prep the zucchini
Wash and trim the zucchini, then grate it using the large holes of a box grater. Place the grated zucchini on a clean kitchen towel or between paper towels and squeeze out as much liquid as possible.
Step 2: Preheat and prep the pans
Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans and line the bottoms with parchment paper.
Step 3: Mix the dry ingredients
In a bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt.
Step 4: Mix the wet ingredients
In a large bowl, whisk together the vegetable oil, granulated sugar, brown sugar, eggs, and vanilla extract until smooth. Fold in the squeezed, grated zucchini.
Step 5: Combine
Add the dry ingredients to the wet ingredients in three additions, alternating with the milk, beginning and ending with the dry ingredients. Mix just until combined after each addition.
Step 6: Bake
Divide the batter evenly between the two prepared cake pans, smoothing the tops. Bake for 30-35 minutes, until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Step 7: Cool
Let the cakes cool in the pans for about 10 minutes, then turn them out onto a wire rack to cool completely before frosting.
Step 8: Make the frosting
In a large bowl, beat the softened butter until smooth. Add the cocoa powder and beat until combined. Gradually add the powdered sugar, alternating with the milk, beating until light and fluffy. Mix in the vanilla extract and a pinch of salt.
Step 9: Frost and assemble
Once the cake layers are completely cool, place one layer on a serving plate and spread an even layer of frosting on top. Add the second layer and frost the top and sides of the cake.
Tips for the Best Chocolate Zucchini Cake
- Squeeze the zucchini thoroughly to avoid a dense or soggy cake.
- Let the cake layers cool completely before frosting to avoid melting or sliding frosting.
- Use good-quality cocoa powder for the richest chocolate flavor in both the cake and frosting.
- Make it a sheet cake for easier serving at a crowd — use a 9×13-inch pan and adjust the bake time to around 40-45 minutes.
Storage
Store the frosted cake covered at room temperature for up to 2 days, or in the refrigerator for up to 5 days. Let refrigerated slices sit at room temperature for about 15-20 minutes before serving for the best texture.
Final Thoughts
Chocolate zucchini cake is a rich, decadent dessert that just happens to have a vegetable folded into the batter, resulting in an incredibly moist crumb under a layer of rich chocolate frosting. It’s a great way to use up extra zucchini while making something that tastes purely indulgent.
