Prepare white cake mix according to package instructions. Add red food coloring until desired redness is achieved. Bake in a shallow baking sheet pan with 1 inch sides for 12-15 minutes or until cake is done. Cut out hearts with a heart shaped cookie cutter of your choice. (I used a 2-inch cookie cutter.) Refrigerate red hearts. Prepare chocolate cake mix according to package instructions. Grease a bread pan. Pour a small amount of chocolate batter on the bottom of the pan (about 1/4 inch deep). Line red hearts up in a row (touching each other) down the center of the pan. Carefully pour the remainder of the chocolate batter around and on top of the hearts. Bake for about 50 minutes or until toothpick inserted into the chocolate part of the cake comes up clean. Let cool. Remove foil from chocolate frosting and microwave for about 35 seconds or until pourable. pour frosting over top of cake, letting it drip down the sides. When frosting has firmed up, carefully slice cake into individual heart servings.