This lovely dessert is easily assembled by chilling layers of gelatin and condensed milk. Even sweeter, it's low-fat.
Dissolve one package of flavored gelatin in 3/4 cup boiling water. Add 3/4 cup cold water, then pour the mixture into a 9- by 13-inch glass pan and refrigerate for 1 hour.
Stir together 1/2 cup boiling water and the condensed milk. In a separate bowl, dissolve all the unflavored gelatin in ½ cup cold water for 1 to 2 minutes. Thoroughly mix in 3/4 cup boiling water, then combine this mixture with the milk and let it cool. Add half the mixture to the pan of red gelatin, pouring it over a spatula to slow the stream, and refrigerate for 20 minutes.
Continue alternating layers — gelatin mix, the remaining milk mix, the final gelatin mix — chilling each for 20 to 30 minutes to set it. Create individual servings with a heart-shaped biscuit or cookie cutter.