Put cream cheese, peppermint extract, and food coloring in mixing bowl. Slip plastic bags over hands, and use hands to mix ingredients until well-blended, or beat with electric mixer on low speed.
Add 3 cups of the powdered sugar to the cream-cheese mixture; mix at low speed until blended (dough will be stiff, like piecrust dough).
Line a flat surface with waxed paper (hold in place by taping down the edges), and dust with the remaining powdered sugar. Set the cream-cheese dough in the middle and begin kneading it with hands to incorporate as much powdered sugar as possible, until dough is very stiff.
Roll out the dough with rolling pin, or pat with hands until it's about 1/2-inch thick. Cut with heart-shaped cookie cutters and place on a serving plate. Combine dough scraps and re-roll to create additional hearts.
If desired, decorate by pressing jimmies or sprinkles onto the top or sides of each heart.
Chill uncovered in the refrigerator for at least 12 hours to harden.