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Chocolate Zucchini Cake

A rich, moist chocolate zucchini cake with chocolate chips and glossy chocolate frosting.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 16 slices
Course: Dessert
Cuisine: American
Calories: 315
Ingredients Equipment Method Notes

Ingredients
  

For the Cake
  • 2 cups all-purpose flour
  • 3/4 cup unsweetened cocoa powder
  • 1 1/2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1/2 teaspoon salt
  • 2 teaspoons ground cinnamon
  • 1/2 cup vegetable oil
  • 1/2 cup sour cream
  • 1 cup granulated sugar
  • 1/2 cup light brown sugar
  • 2 large eggs
  • 2 teaspoons vanilla extract
  • 2 cups zucchini finely grated, lightly squeezed if very wet
  • 1/2 cup milk
  • 1 cup semi-sweet chocolate chips
For the Chocolate Frosting
  • 1/2 cup unsalted butter softened
  • 1/3 cup unsweetened cocoa powder
  • 2 1/2 cups powdered sugar
  • 1/4 cup milk plus more as needed
  • 1 teaspoon vanilla extract
  • 1 pinch salt

Equipment

  • 1 9x9-inch baking pan lined with parchment or greased
  • 2 mixing bowls
  • 1 whisk
  • 1 spatula
  • 1 hand mixer for frosting, optional but helpful
  • 1 box grater for zucchini

Method
 

Make the Cake
  1. Preheat the oven to 350°F. Line a 9x9-inch baking pan with parchment paper or grease it well.
  2. In a medium bowl, whisk together the flour, cocoa powder, baking soda, baking powder, salt, and cinnamon.
  3. In a large bowl, whisk the oil, sour cream, granulated sugar, brown sugar, eggs, and vanilla until smooth.
  4. Stir the grated zucchini into the wet mixture. If the zucchini is very watery, lightly squeeze out excess moisture first.
  5. Add the dry ingredients to the wet ingredients, alternating with the milk, and stir just until combined. Fold in the chocolate chips.
  6. Spread the batter evenly into the prepared pan and smooth the top.
  7. Bake for 32 to 35 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs but no wet batter.
  8. Cool the cake completely in the pan before frosting.
Make the Frosting
  1. Beat the softened butter until creamy. Add the cocoa powder, powdered sugar, milk, vanilla, and salt.
  2. Beat until smooth and spreadable, adding a little more milk if needed.
  3. Spread the frosting over the cooled cake, then slice and serve.

Notes

Grate the zucchini finely for the best texture. Do not overmix the batter. Lightly squeeze zucchini only if it is excessively wet. Let the cake cool fully before frosting. Store covered at room temperature for up to 2 days or refrigerate for up to 5 days.