Sift the icing sugar. Beat the egg whites with the whisks of the hand mixer until stiff. Stir in icing sugar by the spoonful. To spread the biscuits, remove approx. 5 heaped tablespoons of beaten egg whites. Mix almonds, vanillin sugar, cinnamon and bitter almond flavour into the remaining beaten egg whites.
Roll out dough between 2 layers of baking paper 1/2-1 cm thick. Cut out stars (approx. 5 cm Ø), knead the rest and roll out. Spread the stars on 2 baking trays lined with baking paper and coat with egg white icing.
Bake in the preheated oven on the lower rack (electric oven: 150 °C/ convection oven: 125 °C/ gas: level 1) for about 15 minutes.