Beat the eggs with sugar, vanilla sugar and butter until frothy. Mix the flour with the baking powder, add to the egg mixture and stir everything into a smooth dough (hand mixer), then fold in the nuts and fruit, if you like, you can also add orange peel and lemon peel to the dough.
Pour the dough into a greased loaf pan and bake in a preheated oven at 180 degrees (convection) for about 60 minutes until golden brown. Let the cake cool completely in the tin.
Beat the egg white with a pinch of salt until stiff, gradually pour in the powdered sugar. Take the cake out of the mold and cover with the icing sugar.