Mix flour, baking powder, egg yolk, salt, cinnamon, vanilla sugar, sugar and cool fat in flakes to a smooth short pastry. Wrap in cling film and refrigerate for approx. 1 hour.
Roll out the dough on a floured work surface until it is about 3 mm thin. Cut out small rectangles (7 x 3 cm). Brush with egg white and cover with the hazelnuts. Press the nuts firmly. Mix sugar and cinnamon and sprinkle on top.
Place the biscuits on two baking trays lined with baking paper and bake in the preheated oven (electric oven: 200 °C/ gas: level 3) one after the other for about 15 minutes. Results in about 50 pieces.