With a food processor or pastry cutters, combine flour, butter, sugar, egg, baking powder and vanilla sugar to form a dough. Chill in the fridge 1 hour.
Preheat oven to 180 degrees C and grease a baking sheet. Roll out the dough to about 4mm thick and cut out stars of two different sizes. Place on the baking sheet.
Bake 8-12 minutes (depending on thickness). Allow to cool slightly and spread the back of the smaller stars with jam. Press onto the larger stars and let cool completely. If you like, dust with icing sugar.