Rainbow Birthday Cake with Mocha Frosting! {dairy free & vegan}

I got my first sunburn of the summer this weekend while spending the day at the beach. Granted, I was wearing a sweater, and it took several hours to get a little bit of pink on my nose and forehead, but still. 

Beach. Sunburn. Birthday cake. Good times. 

Now, it was no ordinary birthday cake, but, then again, it was no ordinary birthday girl. E and I have been friends since high school, and she has always been one of my biggest cheerleaders, whether I want the attention or not. I hope you all each have someone (or a few someones) like that in your life.

Rainbow Birthday Cake 
This cake is not as complicated as it looks, but you do need to have several hours to devote to it. I baked my layers on Friday afternoon and put the whole thing together on Sunday morning. If you do them in separate steps, wait for the layers to cool completely, then wrap them each tightly in plastic wrap and place in the refrigerator until you're ready to layer and frost the cake.

I made mine dairy free, but the recipe works with the same quantities of real butter and milk. Please add 1/2 tsp salt to the cake batter.

I like this frosting because it is egg free, and avoiding raw eggs at a picnic seemed like a good idea.

White Rainbow Cake - Dairy Free via Whisk Kid
2 sticks vegan butter at room temperature
2 1/3 C sugar
5 egg whites at room temperature
2 tsp vanilla
3 C flour
4 tsp baking powder
1 1/2 C almond milk at room temperature
Red, orange, yellow, green, blue, and purple gel food coloring. liquid food coloring will make pastel layers

Preheat the oven to 350 degrees F. Oil and line your 9" cake pans with parchment paper. Unless you have 6, you'll need to reuse them.

Sift together the flour and baking powder (and salt, if using real butter).

Weigh a large mixing bowl. Either note it's weight or tare the scale. Use that bowl to cream the butter and sugar, and then add your egg whites a little at a time (it's easier to separate them while they are still cold, so do that when you first take them out). Add the vanilla and mix until thoroughly combined. Then, alternating between the flour mixture and milk, add each in two parts (flour, milk, flour milk).

Now weigh your bowl + batter and determine the weight of the batter. Divide that weight by 6, and then separate 6 roughly equal amounts of batter into separate bowls. Add a good amount of food coloring to each bowl and whisk to incorporate.

Pour into cake pans and bake each layer for 15 minutes. When you remove each pan, allow the cake to cool in it for about 10 minutes, then flip onto your cooling rack to finish cooling completely.

Mocha Frosting - Vegan
I used 2.5 batches of this on my cake, but unless you have a stand mixer (I think?), I would recommend making it at least the two separate times. If I had made it all at once, I'm pretty sure my hand mixer would have started to smell burny.

1 stick vegan butter at room temperature
3 C confectioners sugar
1/3 C cocoa
1/4 C strongly brewed coffee at room temperature (ish. NOT an exact measurement)

Cream the butter and then add the sugar and cocoa a little bit at a time. Add the coffee slowly, until you've reached the desired consistency. It should take 10 minutes or so to combine everything and beat it enough to give it some volume.

Assemble the Layers!
Stack the layers in whatever order you'd like, and frost just like you would any other cake. This and this are good tutorials if you need instructions or a refresher.

It should be fine at room temperature, but my frosting definitely showed signs of slipping when it was outside for a while, so refrigerate it before you do that and keep it out of the sun.