To make the cake
215g (1 3/4 cups) all-purpose flour, 75g (3/4 cup + 1 teaspoon) Dutch-processed chocolate powder, 1/2 teaspoon salt, 400g (2 cups) granulated sugar, 2 large eggs 120ml (1/2 cup + 2 tablespoons) vegetable oil, 240g (1 cup), creme fraiche, or sour cream, and 240ml (1 cup) hot coffeeButtercream
- 100g 70% dark chocolate, chopped,180g ( approximately 6) eggs whites, 350g unsalted butter. Soft at home,65g (1/4 cup), pure hazelnut paste. It can also substitute with a good chocolate hazelnut spread. A pinch of salt.
- Pre-heat oven to 350F (180 C). Line three 8-inch (20 cm) cake pans using parchment paper.
- Combine the flour, cocoa powder, baking soda, baking powder, salt, and sugar in a large bowl. Add the sugar.
- Mix the oil, eggs, and cream fraiche in a bowl until smooth.
- Make a well in the centre of dry ingredients. Whisk the liquids in clockwise order until they are thickened, smooth, and glossy. Slowly add the coffee and whisk until well combined. The batter should be thin. Divide the batter between the pans.
- Bake for 30-35 minutes. The tops should spring back when touched with a skewer. Allow to cool down for 15 minutes. Then, turn the cakes out of their pans onto a wire rack to cool completely. To level, any domed surfaces, use a sharp serrated knife.
- Make the buttercream by placing the chocolate in a heatproof bowl. The bowl's base should not touch the boiling water below. Stir until the chocolate is melted. Then, remove from the bowl and allow to cool.
- Next, add the egg whites to the bowl of a stand mixer. Place it on top of the saucepan with the water. Whisk constantly until the mixture reaches 160F (71 C). Once the sugar has dissolved, the mixture will feel hot to the touch. The bowl should be immediately removed and placed on a stand mixer fitted to the whisk attachment. Mix on high speed for 5 to 7 minutes until you have a thick, glossy meringue. The whisk can be switched for a paddle attachment. Once the meringue is thick and glossy, add the butter one tablespoon at a while until it's all gone. Slowly stream in the chocolate, then reduce the speed. Add the hazelnut paste (and salt) to the mixture. Continue beating until smooth and creamy. You can now use the buttercream immediately.
- Place the first layer, cut side down, on a plate. Spread 3 tablespoons buttercream on top. Apply gentle pressure to the next layer. Turn the cut side down and frost it the same way. The final layer is added. The remaining buttercream should be used to cover the cake. Let it cool before you serve.