Knead the butter or margarine with powdered sugar, vanilla sugar, egg yolk, flour and the grated hazelnuts to make a shortcrust pastry. Chill for half an hour, then do not roll out too thinly. Cut out stars and place on a baking sheet lined with baking paper.
Bake until golden at 180 ° C and allow to cool. Brush the stars with the dissolved hazelnut glaze and sprinkle half of them with chocolate flakes.