Put the flour in a bowl and add the butter in pieces. Knead until crumbly with the dough hooks of the hand mixer. Add icing sugar, vanillin sugar and egg yolks and knead to a smooth short pastry. Then continue kneading briefly with floured hands and form into a flat loaf. Wrap dough in foil and chill for about 2 hours.
Roll out the dough on a floured work surface approx. 0.4 cm and cut out approx. 30 biscuits with a round waved biscuit cutter (approx. 7.5 cm). Knead and roll out the dough again and again until the dough is used up. Place the biscuits on two baking trays lined with baking paper and use the biscuit stamp (approx. 7.5 cm) to press in a pattern. Bake the trays one after the other in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 14 minutes until golden brown. Take out the biscuits and let them cool down.