1Heat oven to 400°F. In large bowl, beat 1 cup powdered sugar, the butter and vinegar with electric mixer on medium speed, or mix with spoon. Stir in remaining cookie ingredients except food color. Divide dough in half. Mix food color into one half. (If dough is too dry, stir in milk, 1 teaspoon at a time.)
2On lightly floured cloth-covered surface, roll dough 1/8 inch thick. Cut into heart shapes with various sizes of cookie cutters. Place smaller hearts on larger hearts of different color dough if desired. On ungreased cookie sheet, place shapes about 2 inches apart.
3Bake 5 to 7 minutes or until set but not brown. Cool 1 to 2 minutes; carefully remove from cookie sheet to cooling rack. Cool completely, about 30 minutes.
4In medium bowl, mix all frosting ingredients until smooth and spreadable. Tint with food color if desired. Spread frosting on cookies.