Separate the eggs. Mix the icing sugar with the butter until foamy, gradually stir in the 6 egg yolks and stir everything well. In the meantime, beat the egg whites until stiff.
Stir the vanilla sugar and the grated nuts into the egg yolk mixture. Add the flour, baking powder and the coarsely chopped chocolate. Fold in the egg whites. Bake the cake in a preheated oven at 150 ° C for about 75 minutes.