MAKE THE CAKE: Preheat the oven to 350 degrees. Line two 8-inch round cake pans with parchment paper and grease with nonstick spray.

In the bowl of a stand mixer, using the paddle attachment, mix the cocoa powder, sugar, brown sugar, flour, baking powder, baking soda and salt until well combined.

In a 4-cup measuring cup, whisk the eggs, oil, vanilla and whole milk until emulsified.

With the mixer on medium-low, slowly drizzle the egg mixture into the dry ingredients to form a thick batter.

Add the hot coffee in four additions, waiting until each addition is fully incorporated before adding the next. Use a spatula to scrape the sides and bottom of the mixer bowl to ensure all ingredients are well combined.

Divide the batter evenly into the prepared cake pans. Bake until a toothpick inserted into the center comes out clean, for 40 to 45 minutes.

Let cool for 15 minutes. Carefully run an offset spatula around the edge of the cake pan, then flip out the cakes, remove the parchment and transfer to a cooling rack; cool completely.

MAKE THE BUTTERCREAM. Bring a small saucepan filled with 1-inch of water to a simmer.

Meanwhile, in the bowl of a stand mixer, whisk the egg whites, sugar and salt to combine.

Place the mixing bowl over the simmering water and whisk until the mixture is thickened, very warm to the touch and the sugar is completely dissolved, about 4 minutes.

Transfer the bowl to the stand mixer and whip, with the whisk attachment, on medium for 2 minutes. Increase the speed to high and whip until the bowl is room temperature and stiff peaks form.

Reduce the speed to medium-high and add the butter, a tablespoon at a time, and whip until fully incorporated and thickened.

Switch to the paddle attachment and beat until smooth.

Add the Nutella and mix, scraping the sides and bottom of the bowl, as needed, until well combined.

To ASSEMBLE. Trim the tops of the cake to create a flat surface.

Cut each cake in half to create a total of four layers.

Secure an 8-inch cake board to a rotating cake stand with a dab of the buttercream.

Place a cake layer onto the board.

Using an offset spatula, spread 1 ⅓ cups of the buttercream over the cake layer.

Repeat twice more.

Top with the remaining cake layer, bottom side up.

Crumb coat the cake with a light layer of the buttercream.

Refrigerate the cake for 1 hour or freeze for 30 minutes.

Meanwhile, place 1 cup of the buttercream into a piping bag fitted with a medium-sized star tip; set aside.

Frost the tops and side of the cake with the remaining buttercream.

Refrigerate for 30 minutes or freeze for 15 minutes.

Meanwhile, MAKE THE CHOCOLATE GANACHE. Place the chocolate in a heatproof medium-sized bowl.

In a small saucepan, bring the heavy cream and corn syrup to a steady simmer.

Pour the hot cream mixture over the chocolate, let sit for 2 minutes, then whisk until completely melted and smooth.

Transfer the chocolate to a squeeze bottle.

Drizzle the chocolate where the top and side of the cake meet, allowing it to drip down the sides.

Pour a puddle of the ganache onto the top of the cake and spread it evenly with an offset spatula.

Let the ganache set for 10 to 15 minutes before piping florets along the rim of the top of the cake. Serve immediately or refrigerate for up to 2 days. Bring to room temperature before serving.