In a small bowl, stir the powdered sugar together with enough cream to form a thick, firm froasting. Spoon the frosting into a small pastry bag fitted with a small round writing tip or a plastic freezer bag with a tiny hole cut in one corner. Holding the pastry tip or plastic bag about 1 inch above the cookie and moving it slowly, pipe hair, a mouth, shoes, and whatever else you like for decoration on each cookie. Draw a frosting bow or bow tie at the neck, or outline a dress or jacket. Or create any whimsical design you choose. (Sometimes I look at pictures of decorated gingerbread cookies for ideas.) Let the cookies sit until the frosting is firm.