Put flour, hazelnuts, sugar, vanillin sugar and salt in a bowl. Add butter in pieces. Knead first with the dough hooks of the hand mixer, then with your hands briefly to a smooth dough
Carefully form the dough into 3 equal-sized rolls (approx. 3 cm Ø) and chill for approx. 2 hours. Cut into approx. 1 cm thick slices. Place on 2 baking trays lined with baking paper and press in lightly with the help of a fork crosswise. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) one after the other for 10-13 minutes. Remove and let cool off. Dust with icing sugar
Waiting time 2-3 hours