In a bowl, mix the ground almonds, sifted powdered sugar and cinnamon with a whisk. Add the egg white (not beaten !!!) and the almond liqueur and mix everything with a hand mixer with the dough hook. Then knead into a smooth dough with your hands.
Roll out the dough in portions on a work surface dusted with powdered sugar, about 1 cm thick. Now stars are cut out and placed on a baking sheet lined with baking paper. If the dough sticks to the cookie cutter, dip it into powdered sugar every now and then.
Then beat the egg whites very stiff and gradually add powdered sugar and keep beating. Brush the stars with the egg white mixture and bake in the preheated oven with convection at 150 ° C for about 10 - 15 minutes (or until the egg white begins to turn brown).
The amount makes about 100 cinnamon stars, depending on the rolled out thickness of the dough. If the dough sticks too much to the work surface, the dough can also be rolled out between two layers of cling film. Let the baked cinnamon stars cool down and then store them in tins.