Heat oven to 350°F. Bake cookies as directed on package. Cool on cookie sheets 1 minute. Using 1-inch heart-shaped cutter, cut the centers out of 12 of the cookies. Set aside for another use. Remove from cookie sheets to cooling racks. Cool completely, about 15 minutes.
In small bowl, stir frosting and 1 drop red food color until well blended. Spread 1 tablespoon frosting on bottom side of each of the 12 uncut cookies. Top each with cookie with center cut out; press together gently. Sprinkle heart centers with sugar. Store loosely covered.