How to cook
Heat the oven to 329°F (165 °C).
Prepare 2 cake forms, 9″ (23 cm) in diameter maximum, with removable sides, oiled and covered with baking paper.
1. Mash the hazelnuts in half with a wooden mallet and roast in a dry pan on moderate heat for a few min. or until they start giving off their aroma. Then put them in a blender and blend into coarse pieces.
2. Beat the eggs and sugar with a mixer until whitened. Through a large sieve, carefully add the flour, baking powder, cocoa and hazelnuts but set aside about 3 1/3 tbsp (50 g) of the mixture for decoration. Pour the rest into the cake forms evenly.
Bake at 329°F (165 °C) for 20-25 min. or until your toothpick comes out dry when you poke it in the middle. Leave them to cool on a cooking grid.
Melt the chocolate in a water bath. Leave it to cool to room temperature.
Beat the butter with a mixer until whitened and add all the melted chocolate to it spoon by spoon. Add the wafers that you've crumbled by hand and the Nutella spoon by spoon. Stir carefully with a spatula until homogeneous.
Assembling the layers:
Release the fully cooled cake layers from the baking paper and cut each into 2 - for a total of 4 layers. Place the 1st cake layer in a cake platter and smear it with part of the cream, then alternate cake layer, cream, cake layer, cream, while smearing with cream on top.
Stick the hazelnuts along the sides of the cake. Place a few Ferrero Rocher bonbons on top. Put the cake in the fridge for at least 4 hours. Before serving, take it out for 15 min. to relax and cut it with a knife dipped in warm water and dried.