Cream butter, sugar and vanilla sugar, add eggs one by one. Alternately add the flour mixed with baking powder and the liquid. At the end add the rum.
You can also add only the egg yolks at the beginning instead of the whole eggs and fold in the stiff snow at the end.
The batter should be somewhat viscous and flow well from the spoon.
Bake the waffles one by one in the waffle iron.
The waffles can be supplemented with ice cream, chocolate sauce, fruit, etc. as desired.