In Alsace, people don't say "Christmas cookies" but "bredele", and every family bakes several kinds from late November. Butterbredele are the simplest and best loved: butter, sugar, an egg and flour, cut into little stars and hearts, glazed like a shiny new coin.
What makes a good Butterbredele: a creamed dough rested long in the cold (overnight is ideal), barely 3 mm thick, and a double egg yolk glaze that gives it a caramel varnish. They're best after two or three days in the tin, once the butter has settled in.