Put butter, sugar and vanilla sugar in a bowl and stir thoroughly until foamy. Gradually stir in the sifted flour and cornstarch. Shape the dough into small balls, flatten them a little and use a fork to make patterns. Place on a baking sheet lined with baking paper.
Bake in the preheated oven for approx. 8 - 12 minutes at 180 ° C - 200 ° C.