Mix the butter with the powdered sugar and vanilla sugar until frothy. Add the flour and cornstarch to the butter mixture and stir everything together well.
Shape the dough into balls and place them on a greased tray. Use a fork that has been previously pressed into flour to make a pattern.
It is important that the baking temperature is not set too high. So do not bake too dark at 180 ° C for about 15 minutes.