Chocolate Hazelnut Zucchini Layer Cake
The moist and tender layers, enhanced by the subtle addition of shredded zucchini, are perfectly balanced by the rich, nutty flavour of hazelnuts. The cake's center is filled with a luscious chocolate hazelnut buttercream icing, complemented by a generous sprinkling of chopped hazelnuts for added texture and taste. A velvety chocolate ganache cascades over the top, garnished with more chopped chocolate chips and hazelnuts. For an extra touch of elegance, we served sugared zucchini blossoms with each slice, adding a delicate sweetness that beautifully contrasts the deep chocolate flavours.
Ingredients
Cake
- 2 cups all-purpose flour spooned & leveled (not scooped out with measuring cup)
- ¾ cup unsweetened cocoa powder
- 2 teaspoons baking soda
- ½ teaspoon baking powder
- ½ teaspoon salt
- 1 cup canola or vegetable oil
- 1 cup granulated sugar
- ¾ cup packed brown sugar
- 4 large eggs room temperature
- ⅓ cup plain Greek yogurt room temperature
- 2 teaspoons pure vanilla extract
- 3 cups zucchini shredded, then patted dry on a tea towel (about 2 medium zucchini)
Chocolate Hazelnut Buttercream Icing
- 1 ½ cups unsalted butter room temperature, firm to touch
- ¼ teaspoon salt
- ¾ cup chocolate hazelnut spread Nutella
- 3 cups powdered sugar
- ¼ cup 26 g unsweetened cocoa powder
- 1 teaspoon vanilla extract
Chocolate Ganache
- 2 ounces semi-sweet chocolate chips or bars finely chopped
- ¼ cup heavy cream warmed but not boiled
Sugared Zucchini Blossoms (Optional)
- 6 zucchini blossoms stamens removed, washed, dried on paper towels, and cut in half lengthwise
- ½ teaspoon avocado oil
- 1 teaspoon granulated sugar
For Assembly
- ⅔ cup chopped hazelnuts for between cakes
- ¼ cup chopped hazelnuts for topping cake
- ½ cup chocolate chips chopped
Instructions
Prepare the Cake
- Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans and parchment line the bottom.
- In a large bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt.
- In a separate bowl, using a hand blender with a whisk attachment, whisk together the oil, brown sugar and granulated sugar until well combined. Beat the eggs in a smaller bowl, then pour them into the sugar-oil mixture. Whisk to combine. Then add the Greek yogurt and vanilla and blend to combine. Fold in the shredded zucchini.
- Pour the wet ingredients into the dry ingredients, mixing just until combined
- Divide the batter evenly between the prepared pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely. Let the cakes cool rounded side down, so they will be slightly flatter.
Make the Sugared Zucchini Blossoms (Optional)
- While the cakes cool. Preheat the oven to 165°F true convection.
- Carefully place the blossoms on a parchment lined sheet pan. Lightly brush each blossom with oil and sprinkle with sugar on both sides.
- Cook for 20 minutes with the door open, to slowly dry them out.
- Flip the blossoms and cook for 10 minutes with the door closed now. Flip again and cook for another 10 minutes. Flip one last time and cook for 10 minutes more.
- The blossoms will be dry, translucent, and very delicate. Transfer to a wire rack to dry.
Make the Chocolate Hazelnut Buttercream Icing
- In a large mixing bowl, beat the butter and salt until creamy and smooth. Next mix in the hazelnut spread.
- Sift the powdered sugar and cocoa powder together to break down any lumps. Gradually add the powdered sugar and cocoa powder, into the butter mixture, mixing on low speed until combined.
- Lastly, add the vanilla extract and beat until the frosting is light and fluffy.
Prepare the Chocolate Ganache
- Place the chocolate chips in a heatproof bowl. Pour the warmed heavy cream over the chocolate chips and let it sit for 1-2 minutes until chocolate has melted. Stir until smooth, glossy and slightly runny.
Assemble the Cake
- Add a spoonful of the chocolate hazelnut buttercream icing on a serving plate to keep the cake from sliding. Then place one of the cakes on top, rounded side down. Spread a layer of chocolate hazelnut buttercream icing over the top and sides. Sprinkle ⅔ cup of the chopped hazelnuts evenly over the icing.
- Spread the rounded side of the second cake with icing and place it on top. Frost the top of the cake and sides with the remaining buttercream.
- Using a small spoon, take a little of the chocolate ganache, place the spoon at the edge of the cake, then tilt it over the side, to allow the ganache to run down the side forming a drip about halfway down. Repeat this 10 to 12 times around the cake leaving equal spacing between drips (the drips do not need to be exact or consistent in length). Using an offset spatula, spread the rest of the ganache over the top of the frosting, Sprinkle around the edge of the top with the chopped hazelnuts and chocolate chips.
- If you would like, you could garnish with the sugared zucchini blossoms just before serving or serve a blossom on the plate with each slice.
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Notes
- The sugared zucchini blossoms should be used the same day for the best effect but can be reheated to bring back their crispness if needed.
- If the chocolate ganache cools and thickens, carefully warm in a microwave for a few seconds at time until you get the correct consistency for dripping.
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