1 Heat oven to 375°F. In large bowl, stir cookie mix, flour, melted butter and egg until soft dough forms.
2 On floured surface, roll dough 1/4 inch thick. Cut into desired shapes with 3-inch cookie cutters. On ungreased cookie sheets, place cutouts 2 inches apart.
3 Bake 7 to 9 minutes or until edges are light golden brown. Cool 2 minutes; remove from cookie sheets to cooling rack. Cool completely, about 15 minutes.
4 In medium bowl, beat powdered sugar, 2 to 4 tablespoons milk and the vanilla with spoon until smooth and spreadable. If frosting is too stiff to spread, add additional milk, 1 teaspoon at a time. Tint with food color. Spread frosting on cooled cookies. Decorate as desired with candy sprinkles and colored sugars. Let stand about 30 minutes or until frosting is set. Store covered in airtight container at room temperature with waxed paper between layers.