Line two baking trays with baking paper. Let icing sugar trickle through a sieve into a deep plate. Beat the egg whites and 1 pinch of salt with the whisks of the mixer in a bowl until stiff.
Gradually add icing sugar.
Beat the egg white until a thick, creamy mass (= beaten egg white) forms.
Pour 5-6 tablespoons (approx. 120 g) of beaten egg white into a disposable piping bag or a 1-litre freezer bag. Place the bag with the filling in a tall measuring cup and chill.
Mix hazelnuts, almonds, vanilla sugar and cinnamon together. Then, using a dough scraper, fold into the remaining beaten egg white and stir until smooth. Take the dough out of the bowl and knead it with your hands to a smooth ball.
Roll out the cinnamon star dough with a cake roll between two cut open freezer bags or on a work surface dusted with icing sugar to a thickness of about 1 cm.
Remove the upper freezer bag. Cut out the dough with a star-shaped cookie cutter (approx. 5 cm Ø), one after the other. Knead the remaining dough again and again, roll out and cut out a total of approx. 45 sweet stars.
Preheat oven (electric cooker: 150 °C/circulating air: 125 °C/gas: see manufacturer). Take out the cold beaten egg white. Squeeze the bag opening with thumb and middle finger, press the beaten egg white slightly downwards and screw the bag in a few times above the mixture.
Use scissors to cut a small tip off the bag. Spray the beaten egg whites hazelnut-sized on the cinnamon stars and smooth them down with a brush.
Bake the cinnamon stars one by one in the hot oven for about 18 minutes. Remove, place on a cake rack and allow to cool.