Grind espresso powder finely. Sift icing sugar. Beat the egg whites with the whisk of the hand mixer until stiff, adding icing sugar and espresso by the spoonful. Whip until thick and creamy. Remove 5-6 tablespoons (approx. 115 g) of the mixture and set aside.
Stir nuts, almonds, vanillin sugar and cinnamon into the remaining beaten egg white. Roll out the dough between 2 layers of foil (cut open freezer bags) or on a work surface dusted with icing sugar to a thickness of approx. 1 cm. Cut out stars (approx. 5 cm Ø) close together, knead the remaining dough again, roll out and cut out.
Cut out a total of approx. 45 stars and place them on 2 baking trays lined with baking paper. Spread the stars with the egg whites that have been set aside. Coarsely crush the beans and sprinkle on the biscuits. Bake in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) one after the other for approx. 18 minutes. Remove from the oven, place on a cake rack and allow to cool.