One thing I did to get the nice separation was to use a melon ball sized cookie scoop. I used one scoop of batter for each of the 5 colors (blue, green, yellow, orange, and red). I also divided the batter into five clear cups and mixed in the food coloring.
This is what the cupcakes looked like before they were baked.
Here they are fresh out of the oven. Don't they look pretty? I love that you can see the rainbow through the white cupcake paper.
This recipe made 18 cupcakes. I took 4 with me to NH and got them through airport security! Of course I had several people ask me about my cupcakes and ask what bakery I got them from. While I was on the bus to the airport in DC one guy asked me if I got my cupcakes from Georgetown Cupcake. When I told him I made them he said they looked just like Georgetown's. What a compliment. Of course now I'm going to have to visit that cupcakery since I've never been there. As back up cupcakes in case the ones I made got confiscated, I had cupcakes delivered the day after our arrival from Magnolia Bakery in New York. The flavors that I had delivered were Lemon, Caramel, and Red Velvet. We had a taste testing party and think that the Lemon was the clear winner. Sandra's Man preferred the caramel cupcake. So needless to say we had plenty of cupcakes that weekend.
I used a different recipe for the frosting and this one is light, fluffy, and not too sweet.
Fluffy Buttercream Recipe
1/2 cup shortening
1/2 cup butter
4 cups confectioners sugar-sifted
1/4 tsp salt
1 tsp clear vanilla extract
3 oz heavy cream
Cream shortening and butter until fluffy. Add confectioners sugar on cup at a time and continue creaming until well blended.
Add salt, vanilla, and whipping cream. Blend on low speed until moistened. Add additional cream if necessary. Beat at high speed at least 3 minutes until frosting is fluffy.