I made a rainbow cake for Mike's Birthday recently and I have never been prouder of one of my cake creations. I kept seeing rainbow cakes on a few blogs and just googling "rainbow cake" gives you a million posts of instructions on how to make this striking cake, so I thought I was up to the challenge. I always feel adventurous when it comes to a cake for a special someone's birthday.
All you need is two boxes of white cake mix, two batches of buttercream icing and a lot of food colouring. I usually make my own icing using the Wilton recipe. Divide the 2 boxes of batter into six portions and pour into bowls or tupperwares.
Colour each bowl with your desired colours: purple, blue, green, yellow, orange and red. I just used a four-pack of basic primary food colouring and I was able to make all six colours; however, as you can see, the purple and orange didn't turn out as strong as the others. You will probably end up with food colouring everywhere like this:
Bake each portion separately according to the instructions on the box. This may take some time if you only have one 9-inch pan like I do. A good trick to making sure cake doesn't stick to the pan is to coat the pan in shortening first, then dust with flour and shake off the excess and pour in the batter. The cake will come out clean with hardly any crumbs. When you take the baked cakes out, don't be alarmed if the colours don't look as strong on the outside or if the top browned and the colour looks faded. The colours will be at their strongest on the inside when you cut into the cake.
Two boxes of cake mix doesn't seem like a lot, but six layers of cake makes a massive cake. Stack each layer and spread buttercream in the middle of each, then pipe a circle of buttercream around the edge of each layer, so they stick together.
Then ice the entire cake. It may take quite a bit of icing to cover up the rainbow outside layers, but just keep at it. I decorated the top of the cake with rainbow sprinkles to add some more colour to the outside. The best part is cutting into the first slice and seeing the rainbow layers. It's really neat and the guests loved it.
My birthday was a few weeks later and Mike made me a rainbow cheesecake, which was also neat. He made a basic strawberry cheesecake, and then swirled rainbow food colouring into the batter.