There's always something special about rainbow baked goods. They have the power to bring a smile to any face. This is one of my favorite techniques to use, so I thought I'd share my process with you!
First you make any lovely white cake mix. I always visit Martha for some hints - she never steers me wrong. I used the cake recipe from here (minus the ice cream bit), but there's tons out there.
Next, I divided out the batter into six different bowls and starting colouring. Now, if you don't want to be pooping black for a week, I would recommend using colour gel (you can find this stuff at any craft or cake store. I use the tried and true Wilton brand, but I'm sure there are others out there). 
After everything has been fully coloured, you carefully pour each colour into your pan. No matter how uneven it looks, you've got to stop yourself from taking a spoon and mixing it together. Just plop each colour on top, one after another. Before you put your pan in the oven, make sure to lift it a couple of inches off the counter and let it fall a couple of times. This will make sure there will be no bubbles in your cake.
After coming out of the oven and cooling for a bit, I dipped my cupcakes with white and dark chocolate (just so the rainbow is hidden until the very end). Just picture yourself picking up a boring white cupcake - thinking that it's nothing special -- than BAM
