For the eggnog cookies, quickly knead all dough ingredients into a dough and wrap in plastic wrap. Leave to rest in a cool place for 3 hours. Then roll out the dough between cling film to a thickness of approx. 3 mm and cut out cookies with a round cutter.
Place on a coated baking sheet, bake in a preheated oven at 170° for about 13 minutes. Allow to cool. Melt chocolate in a water bath.
Beat soft butter and add cooled but still liquid chocolate, beat well and add eggnog and continue beating.
Put 2 cookies together with it at a time. Sprinkle with sugar.