Rainbow Birthday Cake

 One of my besties birthday was this past weekend and naturally I wanted to make him a birthday cake. I saw this layered rainbow cake on a blog I follow a few months ago and I knew at that moment him + the rainbow cake = a match made in heaven. He loved it, everyone loved it, I was happy and considering my blog is in dire need of an update,  I'm going to talk about it.

This is such a fun cake, especially for summer or birthdays or anything festive to celebrate. Some birthday cakes can be so one-note, so instead of just layering cake/frosting/cake, I soaked each layer  in a vanilla syrup and filled it with some blackberry preserves as well. The purple frosting piped on the top and sides is also a blackberry buttercream to keep with the theme. If you don't like blackberries, you can use strawberries, raspberries, etc.

Six Layer Rainbow Cake
(adapted from this recipe)

Vanilla Cake
- 2 sticks [8 oz] butter, room temp
- 2 1/3 cup sugar
- 5 egg whites, room temp
- 1 tbsp vanilla extract
- 3 cups AP flour
- 4 tsp baking powder
- 1/2 tsp salt
- 1 1/2 cups milk [ I used 2%], at room temp

Vanilla/Blackberry Buttercream [2x for entire cake]
(my recipe)

- 6 cups powdered sugar
- 2 cups butter, room temp
- 1 tbsp vanilla extract
- big pinch of salt
- 2 tbsp half & half, cream, milk..or until consistency is right for you
- 3/4 cup blackberry preserves [leave out for the plain buttercream]

What you'll need:
6- 8 inch cake pans
parchment
small offset spatula
large offset spatula
piping bags
tip #844

Preheat the oven to 350F. Prep pans. You will need six 8 inch cake pans, sprayed and lined with parchment circles. You can buy 6 foil pans, or bake the cakes in batches.

To make the cake:
With a mixer- Cream the butter and sugar with the vanilla until a smooth paste is formed. Add the egg whites, one a at a time.
Meanwhile, sift together the flour and baking powder. Add the salt to it and blend it in.
Once the eggs are all added, alternate between wet and dry adding the milk and flour mixture in 2-3 parts. Once the last flour addition disappears into the batter, stop mixing.

Divide the batter into six bowls. It is about 1 cup of batter per bowl, but i weighed them to get as close of an exact measurement as possible. Add food coloring to each to get the desired color and mix well [Tip* I use gel food colorings because they do not thin the batter out like water based ones do]

Pour into pans, and smooth out to make sure the batter is evenly distributed in the pan. Bake for 20 minutes or until toothpick inserted comes out clean. [Tip* If the edges seem to be browning quickly, double sheet pan your cakes to stop the bottom from burning]

Let cool slightly in pan, and flip out, remove parchment and cool completely before frosting.

To frost:
Make the buttercream- Cream butter, add powdered sugar slowly. Add vanilla, salt, and half & half and mix until desired consistency. Reserve half of one batch of buttercream for piping and add preserves to that if inclined.

Layer the cakes onto a cardboard cake round, starting with the purple on the bottom. I always have vanilla simple syrup in my house that I make weekly, so I brushed some onto the cakes. Using my small offset, I spread a thin layer of blackberry preserves onto the layers as well and then a thin layer of buttercream.
Repeat this with all the layers, except do not soak or spread preserves on the top layer (red). Cover the cake with a very thin layer of buttercream, called a crumb coat and Refrigerate at least 1 hour until it sets slightly.

Using a larger offset, spread buttercream all over cake as evenly as possible. Once the cake is completely covered, dip your small offset into warm water and gently smooth out the cake.

Pipe shells, rosettes, or any decorative border around the cake, and write whatever message on top.