Preheat oven 350°F. Spray pan with vegetable pan spray; sprinkle 1 teaspoon colored sugar into each heart shape in the pan. Add water to pink lemonade mix to total amount of water called for on cake mix package directions. Follow cake mix package directions to prepare cake, adding chopped lemon peel. Pour into prepared pan.
Bake 20-25 minutes or until toothpick inserted comes out clean. Cool 10 minutes in pan on rack; remove and cool completely before decorating.