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A slice of frosted chocolate zucchini cake laying on a plate.

Chocolate Zucchini Cake

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  • Author: Julianne Dell
  • Prep Time: 90 minutes
  • Cook Time: 35 minutes
  • Total Time: 2 hours 5 minutes
  • Yield: 10-12 servings
  • Category: Cake
  • Method: Oven
  • Cuisine: American


Decadent chocolate zucchini cake made from layers of rich, fudgy chocolate cake with fresh zucchini, frosted inside and out with chocolatey brown butter frosting.


For the Cake

  • 2 ½ cups grated zucchini (About 2 medium zucchinis)
  • ½ cup (118ml) vegetable oil
  • 4 large eggs, at room temperature
  • 1 tablespoon (15ml) pure vanilla extract
  • ½ cup (120g) sour cream, at room temperature
  • 1 ½ cups (285g) granulated sugar
  • 2 cups (240 g) all-purpose flour, sifted
  • 1 cup (80g) Dutch-processed cocoa powder, sifted
  • 3 teaspoons (12g) baking powder
  • 1 ½ teaspoon (6) baking soda
  • 1 teaspoon (5g) salt
  • 1 cup (236ml) hot brewed coffee

For the Frosting

  • 1 ½ cups (339g) unsalted butter, cold
  • 1 cup (80g) Dutch-processed cocoa powder, sifted
  • 5 cups (650g) powdered sugar, sifted
  • 1 tablespoon (15ml) pure vanilla extract
  • ¼ teaspoon salt
  • ¼ cup (59ml) heavy whipping cream


For the Cake

  1. Preheat the oven to 350°F. Prepare two 8-inch round baking pans, line the bottom with parchment paper, and grease and flour the sides of the pan.
  2. Using the large cheese grater, grate the zucchini with the skin on. Then use paper towels to squeeze out extra water from the zucchini, as much as possible. Refluff the zucchini with a fork. Set aside.
  3. In a large mixing bowl, combine the eggs, oil, sour cream, and vanilla extract. Beat all the ingredients together until well combined. Add the sugar and beat until incorporated.
  4. Sift together the remaining dry ingredients in a large bowl and whisk to combine. Scoop ½ – 1 cup of the dry ingredients into the shredded zucchini and stir to combine, coating the zucchini with the dry ingredients. Then add all the dry ingredients and the zucchini to the wet ingredients. Being mixing and slowly stream in the coffee. Beat at a low speed until well combined.
  5. Divide the batter evenly between the two pans, about 2 ¾ cups of batter each. Bake at 350°F for 30-35 minutes.  Test the cake for doneness by inserting a toothpick into the center of the cake. If the toothpick comes out clean, the cake is done. Remove from the oven and allow to cool completely.

For the Frosting

  1. Divide out 1 cup of butter. Cut the butter into 1 tablespoon size pieces and place in a saucepan. Turn stovetop on to medium-low heat slowly bringing the butter to a boil, stirring occasionally. Once boiling, the bubbles will go from big to small, and once the milk solids start to turn golden brown, stir constantly until the golden color starts to darken. Immediately remove from the heat and pour into a heatproof bowl.
  2. Refrigerate the browned butter for 20-30 minutes until it solidifies but it’s not too hard. This can also be placed in the freezer to speed up the process. Once chilled, stir the browned butter back together with a spoon until the milk solids are mixed back into the butter.
  3. Cut the remaining cold butter into tablespoon-size pieces. Using the paddle attachment, whip the butter for 5-7 minutes, scraping down the bowl occasionally until the butter is whipped and easily spreadable. Then mix in in the browned butter until well combined. Next, add the cocoa powder, and beat until well combined.
  4. Add 3 cups of powdered sugar, the salt, and the vanilla extract and beat at a medium-high speed until well combined, then beat for another 1-2 minutes. Next, add the remaining powdered sugar with the heavy cream, 1 tablespoon at a time, and beat on low speed until sugar and cream are incorporated. Increase speed to medium-high and beat for 3-5 minutes, adding additional heavy cream to thin the frosting as needed.


  1. Level the cake layers if needed. Place a dollop of frosting on your cake board and place the bottom layer of cake on top of that. Place half of the frosting in a large piping bag, then cut off the end of the piping bag.  Pipe the first layer of frosting, pipe in circles working outside edge to the middle. Spread evenly with an offset spatula. Place the second layer inverted of the cake.
  2. Use the piping bag to fill in any gaps between the layers and to create a crumb coat. Using an offset spatula or icing smoother, wipe away the excess frosting, leaving you just enough to coat the outside of the cake. With the remaining frosting, pipe the frosting along the outside edge of the cake using a large open round tip then use an offset spatula to smooth the edges. Run a knife up and down the edges of the cake to create the vertical lines and use any remaining frosting to decorate with.


  • Storage instructions: This can be stored at room temperature in an airtight container for 3 days or in the refrigerator for up 7 days. It’s best served at room temperature.
  • Optional decoration: Grab a chocolate bar (any plain chocolate will work. Use a vegetable peeler and run it over the edge of the chocolate bar to make chocolate shavings.


  • Serving Size: 1 slice
  • Calories: 739
  • Sugar: 74.6 g
  • Sodium: 441 mg
  • Fat: 38 g
  • Carbohydrates: 101.5 g
  • Fiber: 4.9 g
  • Protein: 7.9 g
  • Cholesterol: 129.2 mg