For the hazelnut cookies, put flour, baking powder, vanilla sugar, hazelnuts, sugar, egg and salt in a bowl. Add butter, grated zest of one organic lemon and cinnamon.
Mix with a hand mixer, first on the lowest, then on the highest setting. Now let the dough rest for 20 minutes. Meanwhile, preheat the oven to 150 degrees (top/bottom heat).
Using a coffee spoon, place small mounds of dough 5 to 7 cm apart on a baking tray lined with baking paper.
Bake in the preheated oven on the middle shelf for about 15 to 20 minutes.