Cream sugar and butter together. Add egg, milk, and vanilla; beat well. Stir together flour, baking powder, mace and 1/2 teaspoon salt; blend into creamed mixture. Divide in half. Cover: chill 1 hour. On lightly floured surface, roll each half to 1/8 inch thickness. Cut with cookie cutters. Bake on ungreased cookie sheet at 375 for 7 to 8 minutes. Makes about 52 cookies.