Beat the butter, vanilla sugar and powdered sugar until frothy. Slowly add the flour and mondamine, mix in and knead everything into a smooth dough.
Shape the dough into a roll, cut the roll into short pieces, form small balls out of them and flatten them a little with a fork. If the fork sticks, dip it in a little flour.
Bake the cookies at 180 degrees for 10-15 minutes.