Ferrero Rocher Cake Layers:

1. Preheat the oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.

2. Sift together the flour, cocoa powder, and baking powder, then stir in the hazelnut flour.

3. Whip the eggs on high speed for about 3 minutes, then gradually add sugar and continue whipping until tripled in volume (around 15 minutes).

4. Gently fold in the dry ingredients in three additions, careful not to deflate the egg mixture.

5. Divide the batter evenly between the two pans and bake for about 45 minutes or until a toothpick inserted into the center comes out clean.

6. Let the cakes cool in the pans for 5 minutes, then transfer them to a cooling rack.

Nutella Buttercream:

1. Melt the chocolate in short bursts in the microwave, then let it cool to room temperature.

2. Beat together the melted chocolate, butter, and Nutella until light and fluffy.

Assembling the Cake:

1. Slice each cake horizontally into two even layers.

2. Crush the wafers by placing them in a ziplock bag and crushing them with a rolling pin.

3. Set aside ¾ cup of frosting for decoration. Place a small dab of frosting on the serving platter to secure the first cake layer.

4. Spread ¼ of the frosting over the first layer, sprinkle with ⅓ of the crushed wafers, and repeat with the remaining layers.

5. Cover the sides of the cake with frosting and press the remaining crushed wafers or chopped hazelnuts onto the sides.

6. Pipe 8 stars on top of the cake and place a Ferrero Rocher candy on top of each star.

Serve:

1. Chill the cake until ready to serve. Let it come to room temperature before serving for the best texture.