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Ultra Moist Chocolate Zucchini Cake

Ultra moist chocolate zucchini cake with deep cocoa flavor and a tender, fudgy crumb. Grated zucchini melts into the batter while you bake until a toothpick shows a few moist crumbs, then you finish with a smooth cocoa frosting.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Calories: 420
Ingredients Equipment Method Notes

Ingredients
  

Cake
  • 2 cup all-purpose flour
  • 0.5 cup unsweetened cocoa powder
  • 1 tsp baking soda
  • 0.5 tsp baking powder
  • 0.5 tsp salt
  • 2 tsp espresso powder Optional.
  • 2 eggs Large.
  • 1 cup granulated sugar
  • 0.5 cup brown sugar
  • 0.5 cup vegetable oil
  • 0.5 cup sour cream
  • 2 tsp vanilla extract
  • 2 cup zucchini Finely grated.
  • 1 cup semi-sweet chocolate chips
Chocolate Frosting
  • 0.5 cup butter Softened.
  • 0.333 cup cocoa powder
  • 2.5 cup powdered sugar
  • 3 tbsp milk
  • 1 tsp vanilla extract

Equipment

  • 1 sheet pan

Method
 

Bake the cake
  1. Preheat the oven to 350°F (175°C) and get a 9×13-inch baking pan ready.
  2. Grease the 9×13-inch baking pan so the cake releases easily after baking.
  3. Whisk together flour, cocoa powder, baking soda, baking powder, salt, and espresso powder until evenly combined, with no dry streaks.
  4. Beat the eggs, granulated sugar, brown sugar, vegetable oil, sour cream, and vanilla extract until smooth and glossy.
  5. Stir in the finely grated zucchini until it’s evenly distributed through the wet batter.
  6. Add the dry ingredients to the wet ingredients and mix just until combined, leaving the batter thick.
  7. Fold in the semi-sweet chocolate chips so they’re suspended throughout the batter.
  8. Pour the batter into the prepared pan and spread into an even layer with the batter level.
  9. Bake for 32–38 minutes at 350°F (175°C) until a toothpick comes out with a few moist crumbs.
  10. Cool the cake completely in the pan so frosting spreads without melting.
Make and spread the frosting
  1. Beat the softened butter and cocoa powder until smooth.
  2. Add powdered sugar and mix until thick, then drizzle in the milk while beating to reach a spreadable, fluffy texture.
  3. Beat in vanilla extract until smooth.
  4. Spread the frosting over the fully cooled cake in an even layer.
  5. Slice and serve so each piece shows moist crumbs and melty chocolate chips.

Notes

For the moistest texture, bake only until a toothpick shows a few moist crumbs—overbaking dries the zucchini. Store covered in the refrigerator up to 4 days. Freezing is yes: freeze unfrosted slices for up to 2 months and thaw overnight in the fridge, then frost after thawing. For a dairy-reduced option, use plain lactose-free sour cream and lactose-free milk in the frosting (texture stays very similar).