The repice I used is here : http://www.thecakeblog.com/2011/08/blueberry-rainbow-cake.html
The cake has six layers of gradient color from light blue to dark blue. Mine went from more of a light green to dark teal. However, I think it turned out pretty great.
This recipe was slightly difficult because it used grams, and I doubled it so that I could get 6 layers with 8 inch cake pans. I am not entirely sure I converted all of the measurements correctly.
I started with 9 egg whites, 17 ounced of milk and 3 teaspoons vanilla.
Followed by 4 cups flour, 3 cups sugar, 2 2/3 teaspoons baking powder, 1/2 teaspoon salt and 12 ounces unsalted butter.
Once these were combined, I set about coloring six bowls of batter. My biggest fan is my father, and Father's Day or not, he loves to watch me make my creations.
I added one drop of color for the first bowl, two for the next and so on. However, I ended up adding 15 drops to the last bowl to get it dark enough. At that point I began to get nervous that the icing color would make the cake bitter, so I stopped there.
These were popped in the oven at 350 degrees for 25 minutes.
At this point I started making Lemon Curd for each layer of cake. I used Alton Brown's recipe. http://www.foodnetwork.com/recipes/alton-brown/lemon-curd-recipe/index.html
Be warned any time something says it will take 8 minutes of whisking to thicken, you are looking at a half hour. Hope you have been working out your arms.
This stuff is shockingly simple to make (aside from the arm workout), and is super tasty.
At this point it was time for assembly. I cut the browned edges off of each layer of cake so that you would see the bright color on the inside. A knife proved to be a bad option, and believe it or not kitchen scissors helped me to acheive nice round edges on each layer.
I topped the cake with blueberries that had been cooked down in sugar on the stove top. This was a huge hit with the my hero, greatest supporter and Dad! (P.S. Mom liked it too!)