Beat the fat and sugar with the whisk of the hand mixer until foamy. Stir in eggs bit by bit. Mix flour, baking powder, hazelnuts and cinnamon and fold into the fat-egg mixture.
Spread the dough on a baking tray lined with baking paper and bake in a preheated oven (electric range: 175 °C/ gas: level 2) for approx. 20 minutes. Take out and let cool down. Cut out 4 stars of the largest size first.
Then cut out 4 stars each with the 3 smaller cookie cutters. Put the hazelnut glaze in a bowl and melt it on a hot water bath. Dip the stars in it as you like, put them on baking paper and let them dry.
Apply a small blob of glaze to each of the 4 largest stars and place the next smaller stars on top. Continue like this until 4 cake trees are ready. Leave to dry and dust with icing sugar.