In medium bowl, beat egg whites and cream of tartar with electric mixer on low speed until foamy. Gradually add sugar, beating on high speed just until stiff peaks form. Beat in spearmint extract and food color. Fold in 1/2 cup of the chocolate chips. Onto cookie sheets, drop meringue by tablespoonfuls about 1 inch apart. Bake 2 hours. Turn oven off; let meringues stay in oven with door closed overnight.