HEAT oven to 375 degrees F. Spray baking sheets with no-stick cooking spray.
COMBINE 12 cup shortening, sugar and milk in large bowl; beat at medium speed until well blended. Beat in egg and vanilla extract.
COMBINE flour, salt and baking powder in medium bowl. Beat into shortening mixture at low speed until well blended. Drop level measuring tablespoonfuls 2 inches apart onto prepared baking sheets.
BAKE 7 to 9 minutes. Cool 2 minutes on baking sheets; transfer to cooling racks to cool completely.
COMBINE shortening, powdered sugar, milk and vanilla extract in large bowl; beat at low speed 15 seconds. Scrape bowl.
BEAT at high speed 2 minutes, or until smooth and creamy. Tint frosting to desired shade with food coloring if using. Frost cookies.