Go Back
+ servings
Forward facing shot of a chocolate cake with a slice being pulled out from the left side

Dark Chocolate Zucchini Cake

This Dark Chocolate Zucchini Cake is incredibly moist, filled with rich dark chocolate flavor, and topped with a fluffy dark chocolate swiss meringue buttercream. The zucchini is absolutely undetectable, but it lends the best texture to the cake. Perfect for using up all of the late summer zucchini!

Course Cake, Dessert
Prep Time 1 hour 30 minutes
Cook Time 25 minutes
Total Time 1 hour 55 minutes
Servings 10 -12
Author Molly | Spices in My DNA


For the cake

  • 2 3/4 cups all purpose flour
  • 2/3 cup + 2 tablespoons unsweetened natural cocoa powder
  • 2 teaspoons baking powder
  • 1 1/2 teaspoons baking soda
  • 1 teaspoon espresso powder
  • 1 teaspoon salt
  • 3 large eggs
  • 1 cup sugar
  • 1 cup loosely packed brown sugar
  • 1 cup vegetable oil
  • 1 (3.2 ounce) bar Chocolove 70% dark chocolate, melted and cooled*
  • 1/2 cup plain Greek yogurt
  • 2 tablespoons vanilla extract
  • 3/4 cup buttermilk
  • 2 cups grated zucchini

For the chocolate swiss meringue buttercream

  • 1 1/4 cups sugar
  • 5 large egg whites
  • 3 sticks (1 1/2 cups) unsalted butter
  • 3 bars (9.6 ounces) Chocolove 70% dark chocolate, melted and cooled*
  • 2 teaspoons vanilla extract


For the cake

  1. Preheat oven to 350℉. Grease and flour three 8'' cake pans and line the bottoms with parchment paper. Set aside.

  2. In a medium mixing bowl, combine the flour, cocoa powder, baking powder, baking soda, espresso powder, and salt. Whisk to combine and set aside. In a large mixing bowl, combine the eggs, granulated sugar, and brown sugar and whisk until smooth. Add the vegetable oil, melted and cooled chocolate, Greek yogurt, vanilla, and buttermilk and whisk until combined. Add the zucchini and mix with a rubber spatula until combined.

  3. Add the dry ingredients to the wet and mix with a rubber spatula until just combined. Pour the batter evenly into the pans and smooth out the tops with a spatula. Bake for 23-25 minutes or until a toothpick inserted comes out clean. Let the cakes cool for 10 minutes, then remove them from the pans and let cool the rest of the way on a cooling rack.

For the chocolate swiss meringue buttercream

  1.  In a heatproof bowl, whisk together the sugar and egg whites until smooth and combined. Place bowl over a pan of boiling water, (make sure the bottom of the bowl doesn't touch the water!), and cook until sugar has dissolved, 3-4 minutes. Remove from heat. Pour mixture into the bowl of an electric mixer fitted with the whisk attachment, and beat on medium speed for 8-10 minutes, until mixture is cool. (You can touch the bottom of the bowl to test temperature). Switch to the paddle attachment and increase the speed to medium-high and beat until stiff peaks form, another couple of minutes. Gradually add the butter, 2-3 tablespoons at a time, and beat until smooth. Add the cooled melted chocolate and vanilla and beat until smooth and combined.

To assemble the cake

  1. To assemble the cake, place one layer on a serving plate, and spread the top with buttercream. Top with another layer and spread top with buttercream. Top with the third layer and spread with another layer of buttercream, leaving a little bit left for the sides of the cake. Use the leftover buttercream to "half" frost the sides, to create a "semi-naked" effect. Use an offset spatula or bench scraper to smooth out the sides of the cake. Use the back of a spoon to create the fluffy/swirled effect on top. Cut into slices and serve!

Recipe Notes

*You can either melt the chocolate over a double boiler, or melt it in the microwave in 30-second increments, stirring in between, until melted. Be sure not to overheat the chocolate, or it will seize up!
*The cake layers can be made ahead of time up to 2 days, and kept covered until ready to use. The buttercream is best made day-of!