Chocolate Zucchini Cake

This chocolate zucchini cake is incredibly moist and fudgy with a delicious chocolate flavor and creamy chocolate frosting. The zucchini dissolves as the cake bakes, so you can't tastes it whatsoever. Ultra indulgent - this cake can be made as a layer cake or in a 9x13 inch pan.

Prep Time45

Cook Time40

Cooling2

Total Time3 25

Course: Dessert

Cuisine: American

Keyword: Chocolate Zucchini Cake, Double Chocolate Zucchini Cake

Servings: slices

Author: Fiona Dowling

Equipment

2 8-inch round cake pans with 2 inch sides see Notes for additional pan sizes

Ingredients

Chocolate Zucchini Cake

3 cups grated zucchini about 1 pound (454 grams) zucchini of whole zucchini
2 cups all-purpose flour (250 grams)
3/4 cup Dutch processed cocoa (68 grams) sometimes called specialty dark
1 1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup granulated sugar (200 grams)
1/2 cup unsalted butter (112 grams) melted
1/2 cup vegetable oil (120 ml) or canola oil
3/4 cup brown sugar (158 grams) light or dark
3 large eggs
1/3 cup sour cream (80 ml) or plain Greek yogurt
1 teaspoon vanilla extract
1-2 teaspoons instant espresso powder or instant coffee powder

Chocolate Frosting

1 1/2 cups unsalted butter (340 grams) softened but not starting to melt
3-4 cup powdered sugar (330-440 grams)
3/4 cup cocoa powder (68 grams) sifted
1 teaspoon vanilla extract
1/4 teaspoon salt
4-6 tablespoons heavy cream (60-90 ml) milk

Instructions

Chocolate Zucchini Cake

Preheat the oven to 350F (180C). Line the bottom of the round cake pans with parchment paper and grease the sides. If using a 9x13 inch pan, grease and dust with cocoa powder.
Wash the zucchini. Slice off the ends and grate using a cheese grater. If the strands are long, chop them so that they are about 1 inch in length (you don't need to be exact with this). Blot with a paper towel so that the zucchini isn't dripping wet. Set aside.
In a very large bowl, sift together the flour, cocoa, baking powder, baking soda and salt so that there are no lumps. Add in the granulated sugar. Whisk for about 15-20 seconds until evenly combined. Set aside.
In a large bowl, whisk together the melted butter, oil, brown sugar, eggs, sour cream, vanilla extract and instant espresso powder (optional but recommended). Whisk until you no longer see pieces of egg or lumps of brown sugar.
Make a well in the middle of the dry ingredients and pour the wet ingredients into the well. Gently fold together using a rubber spatula or wooden spoon. Do a few stirs until the mixture looks about 50% combined (you will still see lumps and streaks of dry ingredients.
Add the grated zucchini to the batter. Do a few more stirs by hand, then mix with an electric mixer until you no longer see streaks or lumps of dry ingredients. The batter will be thick. You can do this entirely by hand answell.
Pour the batter into the prepared pans. Bake in the preheated oven for 40-45 minutes for two 8-inch round pans (with 2-inch sides). When the cakes are done baking the top should be set, the sides should be pulling away from the pan, and an inserted toothpick should come out clean. If you're unsure, I recommend baking for a few extra minutes - as this cake is very unlikely to dry out.
Cool the cakes fully. If making a layer cake, cool the cakes in the pans for at least 25 minutes, then carefully invert the pans and continue cooling on a wire rack. If using a 9x13 inch pan, cool the cake in the pan.

Chocolate Frosting

In a large bowl, beat the butter until smooth and creamy.
Add in 2 cups powdered sugar. Start mixing with the mixer on a low speed, then gradually increase to medium speed until combined.
Sift in the cocoa powder and add in the vanilla and salt. Again, start mixing with the mixer on a low speed and gradually increase the speed to medium until combined.
Mix in the rest of the powdered sugar about 1/2 cup at a time, alternating with 1-2 tablespoons of cream or milk until the desired sweetness and thickness is reached.

Assembling the Cake

Ensure the cake/cake layers are fully cooled. If making a layer cake, gently saw off the rounded top of the cake.
For a layer cake, place one layer on the plate/cake stand that you plan to serve it on. Frost the top of the layer with about 3/4-1 cup of frosting. Then place the second layer on top. Frost the sides with a thin layer of frosting as a crumb coat to seal in the crumbs. Then frost the sides and top with swirls of frosting.
For a 9x13 inch cake, simply frost the top of the fully cooled cake with frosting.

Notes

Pan Sizes & Bake Times:
- Two 8 inch (20 cm) rounds with 2 inch (5 cm) sides (as pictured) - bake time 40-45 minutes. Do not use two 8-inch round sandwich tins with 1.5 inch sides - the batter will overflow.
- Two 9 inch (23 cm) rounds - bake time 28-35 minute
- 8 x 8 inch (20 x 20 cm) square pan - divide the cake recipe in half (use 1 egg plus 1 egg yolk), bake time about 30-35 minutes
- 9 x 13 inch (23 x 33 cm) pan - bake time 45-50 minutes, half the frosting recipe
Frosting: You will likely have some leftover frosting, but I find it better to have extra than not enough. For a 9x13 inch cake, you'll need:
- 3/4 cup unsalted butter
- 1 1/2 -3 cups powdered sugar
- 1/4 cup plus 2 tablespoons cocoa powder
- 1/2 teaspoon vanilla
- pinch of salt
- 2-3 tablespoons of milk or cream
Make Ahead Tips: Make the cake layers/cake the day before you plan to serve. Cool fully, then wrap tightly (or cover the pan for a 9x13 inch). Store at room temperature overnight. Make the frosting and assemble the cake the day you plan to serve. Store lightly covered at room temperature until ready to serve. If your kitchen is warm, then store in the fridge.
Storing Leftovers: Store leftovers covered in the fridge for up to 4 days.
Freezing: Unfrosted cake layers can be wrapped tightly, then placed in a freezer bag or container. Freeze for up to 2 months. Thaw the cake in the fridge. Then frost. Do not thaw on the counter as it can make the cake turn gummy.
Nutrition: Details provided are an estimate only and based on 1 slice of cake, assuming that all of the frosting is used and the cake is sliced into 12 uniform pieces.

Nutrition