Pour the flour into a high bowl. Add sugar, vanilla sugar, nuts, butter and egg yolk. Knead into a dumpling for 2 minutes on the highest setting.
Sprinkle the work surface with flour. Form 1/2 cm thick and 5 cm long rolls from the dough, shape into croissants, place on a baking tray lined with baking paper and bake. (fan oven 150 degrees, 25 minutes, baking trays at level 1 and 3).
Mix icing sugar with vanilla sugar on a plate, turn the still warm croissants in it and let them cool down. Makes about 80 pieces.