1 cup Whipped fluffy white frosting (from 12 oz container) red food color
Heat oven to 375°F. In medium bowl, stir cookie mix and flour until well blended. Add butter and egg; stir until soft dough forms.
On floured surface, roll dough to about 1/8-inch thickness. Cut with 2 1/4-inch heart shaped cookie cutter. Generously cover large piece of waxed paper with granulated sugar. Transfer cutouts to waxed paper using pancake turner. Turn each cutout to coat both sides. Place on ungreased cookie sheet.
Bake 5 to 6 minutes or until edges are light golden brown. Cool 1 minute; remove from cookie sheets. Cool completely, about 15 minutes.
Divide frosting into six small bowls. Add the following different amounts of red liquid food color to one of each of the bowls starting with a toothpick, 1 drop, 3 drops, 7 drops, 12 drops and 25 drops to make different shades of pink.
For each cookie sandwich, spread about 1 teaspoon frosting on the bottom of 1 cooled cookie. Top with second cookie, bottom side down; gently press cookies together.