Rainbow Layer Cake

Jamie and my adorable niece Charlotte is coming to visit us for her 6th birthday. (She chose visiting us for the weekend over having a birthday party!) We're going to have a little party for her up here and when my sister-in-law Katie asked if we could get a cake for her, I thought it would be fun to do something special. Enter the rainbow layer cake. (I did try an easier version once before.) Not sure if you've seen this all over the pinterest-sphere, but it's a beautiful cake with six colored layers - red, orange, yellow, green, blue, purple - with white icing in between and on the outside. So it looks like a plain, white cake, but is all rainbow when you cut into it. It is definitely more work than a regular cake, but worth is if you have a little kid to impress.

Ingredients:

Two packages of white cake (pick whatever kind you want)

-follow the instructions on the back and use just the egg whites if that's an option - it will lead to crisper colors

Parchment paper

Food dye (gel would probably work better for brighter colors, but I used regular food coloring)

For buttercream:

1 cup butter, softened (best to leave it out all day or overnight)

1 cup vegetable shortening

2 lb powdered sugar

2 tsp vanilla

4 tbsp heavy cream (you can use milk, too)

Directions:

Heat oven to 350. Grease 2 (or more if you have them) cake pans and add a circle of parchment, also greased. (This makes it much easier to get the cake out.)

Mix up the batter according to the directions (using a little less water if you're using regular non-gel food dye). Put out 6 bowls and evenly distribute the batter between them. I put 1 1/3 cup of batter in each.

Start adding the food dye until you get the colors you want. Be prepared to use a lot of food dye.

Start cooking them. The nice thing is, they're very thin and cook quickly. Spread the batter around almost to the edges of a 9" pan (or all the way to the edges of a smaller pan).

Bake about 10-15 minutes, until a toothpick comes out clean. Let them cool and level off the top so it's flat. This will also help them cool faster.

Orange and red layers.

Yellow and green.

Cooked.

Blue and purple.

My pile of cake scraps - yum! Reminds me of the imaginary food scene in Hook, right?

I wasn't making the cake that night, so I carefully wrapped up each cooled layer in plastic wrap and refrigerated them.

To make the butter cream, cream the butter and shortening over medium speed in a KitchenAid or with a hand mixer for about 5 minutes.

Gradually add the powdered sugar. This takes a while because if you add to much, it puffs out. (It will a little anyway.) Once fully incorporated, add vanilla and cream. Whip on high until fluffy, about 2-3 minutes.

To assemble the cake, put the first color (I started with purple) on top of some wax paper on a plate or flat surface where you plan to keep it.

Spread with frosting and stack the next color in rainbow order.

Using a serrated knife, trim the edges so the sides are flat and even.

Put a thin layer of frosting all the way around to catch any crumbs.

Refrigerate for a few minutes to set it.

Continue frosting a nice, thick layer of the buttercream and smooth it all out. Add any lettering/decoration you want.

It's a great surprise to cut into the cake and see a rainbow.

Here's the birthday girl.

And the inside of the cake.

And a slice.

Aaaand another cake shot. Pretty cool, right? I definitely earned some aunt points.