Tool

• Stand mixer

Three 8‑inch cake pans

Ingredients

For the Cake

• 3 cups all‑purpose flour

• 1 cup unsweetened natural cocoa powder

• 1 tablespoon baking soda

• ¾ teaspoon baking powder

• 1½ teaspoons espresso powder (optional)

• ¾ teaspoon salt

• 1½ cups vegetable oil

• 1½ cups granulated sugar 

• 1 cup light brown sugar, packed

• 6 large eggs, room temperature

• ½ cup sour cream, room temperature

• 1 tablespoon vanilla extract

• 4½ cups grated zucchini (about 3 medium zucchini)

• 1½ cups semi‑sweet chocolate chips

For the Buttercream

• 1 cup semi‑sweet chocolate chips

• ⅔ cup heavy cream, divided

• 5½ cups powdered sugar

• 1½ cups unsalted butter, room temperature

• ½ teaspoon salt

• ⅓ cup unsweetened natural cocoa powder

• 1½ teaspoons vanilla extract

Direction

For the Cake

1. Prepare the pans: Heat the oven to 350ºF. Grease three 8‑inch cake pans with baking spray or butter and flour. Line each base with a parchment round. If you use baking strips, soak and wrap them around the pans for even baking.

2. Mix the dry ingredients: In a large bowl, whisk together the flour, cocoa powder, baking soda, baking powder, espresso powder, and salt. Set aside.

3. Combine the wet ingredients: In a separate large bowl, whisk the vegetable oil, granulated sugar, brown sugar, eggs, sour cream, and vanilla until smooth. Fold in the grated zucchini with a spatula until fully blended.

4. Bring the batter together: Pour the wet mixture into the dry ingredients and stir gently until almost combined—light streaks of flour are okay. Add the chocolate chips and mix just until the batter is fully incorporated and the chips are evenly distributed.

5. Bake the layers: Divide the batter evenly among the pans (about 3⅓ cups / 810g per pan). Bake for 35–40 minutes, or until the centers spring back when touched and the edges begin to pull away from the sides. Cool the cakes in their pans for 10 minutes, then turn out onto a wire rack to cool completely. Remove parchment once cooled.

For the Buttercream

1. Melt the chocolate: Combine the chocolate chips and ⅓ cup of heavy cream in a microwave‑safe bowl or measuring cup. Heat in 30‑second intervals, stirring between each, until smooth. Set aside to cool slightly.

2. Cream the butter: In a stand mixer fitted with the paddle attachment, beat the butter and salt on medium speed until light and creamy, about 3 minutes. Sift in the cocoa powder and mix on low until combined. Scrape down the bowl.

3. Build the frosting: With the mixer on low, gradually add the powdered sugar—about 1 cup at a time—alternating with small splashes of the remaining heavy cream. Once everything is incorporated, mix in the vanilla and the cooled melted chocolate.

4. Whip until fluffy: Increase the mixer speed to medium and beat for 2 minutes, or until the buttercream is airy, smooth, and easy to spread. Transfer 1 cup (236g) of frosting to a piping bag fitted with an open‑star tip (Ateco 869).

For Assembly

1. Layer the cake: Place the first cooled cake layer onto a stand or serving plate. Spread 1 cup of buttercream evenly over the top. Add the second layer and repeat. Place the final layer top‑side down for a flat finish.

2. Frost the cake: Cover the top and sides with the remaining buttercream. For a semi‑naked look, leave a thicker layer on top and use an offset spatula or bench scraper to thin out the frosting along the sides.

3. Finish and chill: Pipe decorative dollops around the top edge using the reserved frosting. For clean slices, chill the cake for at least 30 minutes to firm the buttercream before cutting.

Nutrition -

(Per Serving)

Calories: 1285 kcal Carbohydrates: 150 g Protein: 12 g Fat: 75 g Saturated Fat: 33 g Polyunsaturated Fat: 18 g Monounsaturated Fat: 19 g Trans Fat: 1 g Cholesterol: 166 mg Sodium: 600 mg Potassium: 607 mg Fiber: 8 g Sugar: 113 g Vitamin A: 1194 IU Vitamin C: 8 mg Calcium: 116 mg Iron: 6 mg