Mix the room temperature butter with the sugar until frothy. Then add the cream and 4 eggs. Gradually mix in the lemon peel with a good 1 kg of flour. As long as you knead with your hands, you get a smooth dough.
Chill the dough in a floured bowl for at least 3 hours. It cannot be made into cookies when warm.
After 3 hours, cut off a piece of the dough and roll it out about 1/2 cm thick. Cut out cookies with molds.
Whisk a whole egg and 3 egg yolks together and brush the cut-out cookies with them. If you want, you can also add sugar sprinkles or chocolate sprinkles. Bake in the oven preheated to 150 ° C for about 10 minutes until they are lightly browned.