teaspoon baking powder
Beat margarine and shortening with mixer on high for 30 seconds. Add half flour, egg sugar, milk, baking powder, vanilla and salt. Beat until thoroughly combined. Beat in flour. Divide dough in half and chill about three hours. On lightly floured surface, roll half the dough at a time to 1/8 inch thick. Cut in desired shapes and place on ungreased cookie sheet. Bake 375 degree for 7 - 8 minutes or until edges are firm and bottoms lightly brown. Cool on rack.