In large mixer bowl combine all cookies ingredients. Beat at low speed, scraping bowl often, until well mixed (1 to 2 minutes). If desired, divide dough into 3 equal portions; color 2 portions of dough with desired food colorings. Mix until dough is evenly colored. Wrap in waxed paper; refrigerate until firm (2 to 3 hours). Heat oven to 400 °F. Roll out dough, 1/3 at a time, on well-floured surface to 1/4-inch thickness. Cut with 3-inch cookie cutters. Place 1-inch apart on cookie sheets. If desired, sprinkle colored sugar on some of the cookies or bake and decorate later. Bake for 6 to 10 minutes or until edges are lightly browned. Cool completely. In small mixer bowl combine all frosting ingredients. Beat at low speed, scraping bowl often, until fluffy (1 to 2 minutes). Frost and decorate cookies.