My daughter turned 5 and she wanted a purple rainbow cake. I decided that the rainbow wouldn’t be on the outside, but rather the inside of the cake. So I baked 6 different round cakes each a different color. I used a raspberry filling I made to place between each layer. Once the 6 layers were together I iced the homemade rainbow cake with purple frosting and piped pink hearts and border on the cake.
My daughter was upset she didn’t have a rainbow cake until we cut into it, and then she almost fell over when she saw the rainbow was inside the cake. All of the other parents were amazed at the cake, and to this day I still get asked about this homemade rainbow cake.