Quickly mix all the ingredients to a short-crust dough and leave it in a cool place for one hour. Roll out the dough to a thickness of about 1 cm before cutting into small pieces and forming crescent-shaped cookies. Place the cookies on an ungreased baking tray and bake at a moderate temperature (200°C) for around ten minutes or until they turn a light brown colour. Mix icing sugar and vanilla sugar together, then toss the hot cookies in the mix. Store the cookies in a sealed tin for several days for them to become crumbly.
But make sure they are well hidden so nobody gets at them before you can!