Mix butter, vanillin sugar and icing sugar with the whisk of the hand mixer until creamy. Stir in the egg. Stir in flour. Pour the dough into a piping bag with a star-shaped spout and squirt 10 biscuits each onto 2 baking trays lined with baking paper.
Put in a cool place for about 1 hour. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Remove cookies and let them cool down on a cake rack. Dust the cookies with icing sugar
Waiting time 1 hour