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A slice of chocolate zucchini cake on a plate with a fork at the side

Chocolate Zucchini Cake

Super moist and delicious Chocolate Zucchini Cake. Don't forget to check out my step by step photos and tips above!
Course Dessert
Cuisine American
Prep Time 30 minutes
Cook Time 35 minutes
Total Time 1 hour 5 minutes
Servings 12 people
Calories 389kcal


  • Stand mixer or electric whisk
  • Three 8 inch cake pans


For the Cake:

  • 3 cups all-purpose flour (360g)
  • 1 cup cocoa powder unsweetened natural (100g)
  • 1 tbsp baking soda (18g)
  • 3/4 tsp baking powder (1g)
  • 1 1/2 tsp espresso powder optional (1g)
  • 3/4 tsp salt (4g)
  • 1 ½ cup vegetable oil (354mL)
  • 1 1/2 cup granulated sugar (300g)
  • 1 cup packed light brown sugar (200g)
  • 6 large eggs room temperature
  • 1/2 cup sour cream or plain yogurt, (115g) room temperature
  • 1 tbsp pure vanilla extract (15mL)
  • 4 1/2 cups zucchini about 3 medium, shredded (475g)
  • 1 1/2 cup chocolate chips semi-sweet (265g)

For the Chocolate Buttercream:

  • 1 cup chocolate chips
  • 2/3 cup heavy cream divided (160ml)
  • 5 1/2 cups confectioner's sugar (680g)
  • 1 1/2 cup unsalted butter room temperature (342g)
  • 1/2 tsp salt
  • 1/3 cup cocoa powder (40g)
  • 1 1/2 tsp vanilla (7mL)


For the Cake

  • Heat oven to 350 degrees and prep 3, 8-inch cake pans butter and flour or baking spray. Cut a parchment round for the bottom of each pan and place inside. I always use cake strips, which prevent my cake layers from doming.
  • Mix together flour, cocoa powder, baking soda, baking powder, espresso powder (optional), and salt in a large bowl. Sifting will break up any lumps of cocoa powder but is not a must.
  • Mix oil, granulated sugar, brown sugar, eggs, sour cream, and vanilla together in a second large bowl. If using a stand mixer use a paddle attachment.
  • Add the shredded zucchini to the wet mixture and mix on low to combine.
  • Add the dry to the wet and mix on low until almost combined then add in chocolate chips and mix until distributed. Scrape the bowl down and use a spatula to mix in any stray bits of flour etc.
  • Distribute cake batter evenly to your three prepared pans and bake for 30-35 minutes, or until centers are springy to the touch and a skewer inserted in the middle comes out clean.
  • Allow cakes to cool in pans for a couple minutes then invert onto a wire rack, and remove parchment paper rounds. Allow to cool completely

For the Chocolate Buttercream

  • Melt 1 cup semisweet chocolate with 1/3 cup cream then stir together and set aside to cool.
  • Cream the butter and salt then sift in the cocoa powder and mix until combined.
  • Scrape the bowl down then add the confectioner’s sugar in a few batches alternating with the cream. Add the vanilla and melted and cooled chocolate then increase speed to high and beat for 3-5 minutes until light and fluffy. Scrape the bowl down one last time and mix once more.

For the Assembly:

  • Pipe buttercream onto the first layer. Add second layer and repeat.
  • Apply a thin coat of buttercream to the side and top then smooth.
  • Pipe dollops of buttercream on the top's edge using an 869 or any large star tip.



  • Make sure to measure your flour correctly Adding too much flour to the recipe is the most common mistake. The best and easiest way to measure flour is by using a kitchen scale. If you don't have one then fluff your flour with a spoon, sprinkle it into your measuring cup, and use a knife to level it off.
  • Use three 8 inch cake pans so each layer is high and uniformed.
  • Make sure to prepare your cake pans, grease them in butter then dust them in flour getting rid of any excess. Place a round piece of parchment paper at the bottom of each pan. This will make sure that your cake won't stick and will give you an easy release.
  • The zucchini grates really easily and quickly using the big holes on a box grater. You can use a food processor if you don't have one.
  • If the zucchini seems extra wet squeeze out any excess moisture.
  • Make sure your refrigerated ingredients are at room temperature before starting especially the eggs!
  • To test that the cake is ready insert a small skewer or toothpick into the center of the cake, if it comes out clean it's ready.
  • To get uniform flat layers that are moist inside and out try using cake strips! You can buy a set on the shop page or make your own from foil and paper towels at home. I made a whole blog post on it so check it out if you’re interested!
  • Make sure the cake is cooled completely before frosting.
  • Your butter should be softened at room temperature before making the buttercream or it'll be lumpy and unpleasant.
  • Instead of Chocolate Buttercream, you could use Mocha Frosting, Cream Cheese Frosting, or Swiss Meringue Buttercream instead.
  • I like to use a star tip to pipe some frosting around the top edge of the cake. I used an 869 tip but any larger star tip will work well.
  • You can use the batter to make cupcakes instead of a whole cake.
  • Storage - this cake will keep well for 4-5 days or can be frozen for up to 3 months. Wrap in plastic wrap and foil then defrost thoroughly before serving.


Serving: 1piece | Calories: 389kcal | Carbohydrates: 40g | Protein: 4g | Fat: 9g | Saturated Fat: 3.5g | Polyunsaturated Fat: 1.5g | Monounsaturated Fat: 3g | Cholesterol: 12.7mg | Sodium: 213mg | Potassium: 170mg | Fiber: 2.4g | Sugar: 22g | Vitamin A: 370IU | Vitamin C: 2.2mg | Calcium: 27mg | Iron: 1.8mg