Mix flour and cream of tartar; add butter and mix until crumbly. Slowly add light cream. Chill. Divide dough in half. Color half of the dough with green food coloring. With a small quantity of dough, roll into a pencil shape from each color. Twist the pencil together and press ends together to form a wreath. Dip wreath in slightly beaten egg white and then into granulated sugar. Bake at 400 degrees for 20 minutes on greased sheets. Makes 2 dozen.