Mix the butter, powdered sugar, vanilla sugar and egg white. Mix the flour and cornstarch and sieve, stir 2/3 into the mixture and knead in the rest. If the dough is still too sticky, it needs to be in the refrigerator for a few minutes.
Form an approx. 1.5 cm thick roll, cut approx. 1.5 cm thick slices and then place them on the baking sheet in a round shape. Press a little flat with a floured fork so that the notches are clearly visible. Now put the cookies in the non-preheated oven and bake at 170 ° C (hot air) for 8-10 minutes.