The one from Omnomicon where she mixed a bunch of food coloring into the batter and baked it together.
Well I found another rainbow cake that I am in love with and I think I am going to make it for myself for my birthday...in 6 months! Or I am going to have to find a reason to make it sooner:
You have to go to Meg Duerksen's blog, Whatever, and check out the pictures of this cake. Her pictures are ginormous the cake is even prettier the more life size it is!
She just added food coloring to white cake mix and baked the layers separately...I want to try it with different flavors too!!