Very easy to make.
Ingredients: 200g butter, 200g flour, 200g cheese (recipe said Gouda, I took parmesan ...), 1 egg, nutmeg and pepper.
Mix well and put in the freezer for 15 min. Roll out the dough and take out the X-mas cookie cutters. The original recipe suggested sesame seed, poppy seed and caraway as toppings with on some egg+milk mixture. I used the sesame and some crushed rosemary with olive oil. I also sprinkled some salt on top.
Bake for 10-12 min. at 200°C.
Should keep well for a couple weeks in a jar, unless eaten. To make that batch it took me about an hour.
Also found here: de.wikipedia.org/wiki/K%C3%A4segeb%C3%A4ck