This rainbow heart surprise cake has to be the cutest thing ever! It is also so very easy to do. For any party or occasion, this is the cake you want to receive. All you need are six cake mixes, a loaf pan, and a baking sheet. This also calls for bright food coloring and fondant. Pick colors that are bright enough to stand out, so a vanilla cake will work best. You will be so very pleased with the results. Have on hand wax paper to line each one of your pans, and heart shaped cookie cutter.
To get started, you want to mix your six cake mixes together. Mix until well blended. Then divide up the six cake mixes evenly. You want to fill up six pastry bags with the cake mix. Make sure that you add the food coloring beforehand. Mix very well so the color is even. When you get the colors mixed in, pipe each one in swirls on the baking sheet. These will become the rainbow colored hearts. Cover your baking sheet with the wax paper, so the cake does not stick. Swirl each color until you are done. It will look like a happy rainbow. Bake this in the oven for about 20 minutes. Test it, to make sure it is baked through. You do not want the cake to get too browned on top. Once the cake is done, take it out and let it cool.
Once the cake is cool, cut the top off the cake that is brown. You also want the cake to be even. Take your cookie cutter and start cutting out the heart shapes. You want to get as many shapes as possible. It will be okay to have too many. If you do not have enough, the heart shape will fall over. Cut the ends off the heart shapes to make sure the color shows on both sides. After you get all the shapes cut out, place them in the freezer overnight. You will now take a loaf pan and line it with foil or wax paper. You want to make sure that your cake will not pour over. Mix two more vanilla cake mixes. Take about two cups of cake mix, and place it in the bottom. Bake this for about 15 minutes. This will be the bottom of your cake. After it is done, take out your heart shapes. You want to line up your heart shapes in a row. Fit them tightly in the pan. Place the rest of your cake mix around the hearts and on top. Bake for about 30 to 40 minutes. You can test with a toothpick. Cover the cake with a bright fondant. You have just now made the most lovely rainbow heart cake.