Knead the flour, ground hazelnuts, sugar, vanillin sugar, salt, cold fat and egg into a smooth short pastry. Cover and chill for about 30 minutes. In the meantime mix whole hazelnuts, rum raisins and chocolate drops.
Roll out the short pastry on a floured work surface to a thickness of approx. 1/2 cm. Cut out circles (approx. 6 cm Ø) and brush with egg white. Spread 1 tsp hazelnut mixture on each half of the circles.
Overfold the other half. Place the cookies on a baking tray covered with baking paper. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 15 minutes. Let them cool down and dust with icing sugar.
Results in about 50 pieces.