Mailänderli (Milano cookies, Christmas treat)

Ingredients for approximately 80 cookies (depending on the size of a single cookie):

Stir butter in a bowl until it is smooth.
Add sugar, salt and 3 eggs, stir until ingredients are evenly distributed.
Grind the skin of the lemon and add to the mixture of the previous step.
Add flour, knead to a soft dough.
Cover the dough and let rest for about 2 hours in a cool place.
Cut dough in parts and roll out on a flat, with flour covered surface, approximately 5 mm (0.2 inches) thick. Put out different shapes and put them on a baking sheet covered with baking paper.
Let cool for about 15 minutes.
Before baking, sweep with the yellow of an egg.
Bake for about 10 minutes in the center of the pre-heated oven at 200 °C (400 °F).
Let cool completely before serving.