Beat the softened butter until smooth and gradually stir in the sugar and vanilla sugar. Stir in the 2 eggs one after the other. Mix flour with baking powder and sieve. Gradually stir in alternately with the Bailey`s. Now stir in the hazelnut brittle and cocoa and pour the dough into a 22-inch greased and crumbled Guglhupf pan.
Bake in the preheated oven at 175 ° C in the lower third for about 45 minutes. Do not turn the cake out for 10-15 minutes after baking.