Beat the butter, sugar and 5 egg yolks in the food processor for a long time until a thick, almost white cream is formed. Season with lemon peel and mace. Finally work in the flour quickly. Divide the dough into 2 portions, shape into a roll and put in a plastic bag. Chill in the refrigerator overnight.
Do not roll out the dough rolls until the next day, each half a centimeter thick, by no means too thin. Cut out stars. Whisk the rest of the egg yolk with the cream, brush the stars with it. Sprinkle with the granulated sugar.