Make a dough out of
flour, butter, sugar, cacao and egg yolk and put in the fridge for one
hour. Roll the dough out and cut out Christmas trees by hand or with
the help of a cardboard model or a cookie-form.
Bake 12-15 minutes at 180 degrees Celsius.
Cool down for one hour. Make two colors of icing with the icing sugar
and food coloring. Dip in a tip of a knife and make Christmas decorations
in the tree.
Mix all the ingredients
except the food coloring, divide the dough in two and add a few drops
of red to the one and green to the other half.
Make lines of green on a baking tray, using a pastry bag, and consequently
adjacent lines of red. Bake 10 minutes at 180 degrees
The Worldcook site has also a
page for Christmas cookies.