Rainbow Cake

The Rainbow cake that I made was a recipe my friend Tracy sent me from Whisk Kids.  I looked at a lot of other recipes, but she was on Martha Stewart making this exact cake, so with the on-line tutorial and her instructions this cake was a breeze to make.  Heres the recipe...


Super Epic Rainbow Cake
I'm adding a disclaimer here: THERE IS A LOT OF FROSTING/BUTTER IN THIS CAKE. I used a lot because I wanted the cake to be very striking visually. It is intentional. Put in less if you want. Also, I'm not forcing you to eat this entire cake by yourself, so - seriously - quit freaking out about the butter. 

Watch me make this cake with Ms. Stewart on The Martha Stewart Show!

Printable Recipe

White Cake (but not really)
I made things difficult on myself and altered a coconut cake recipe for this. I don't know why I didn't just make a white cake from a white cake recipe, but.... I didn't. Here's the source if you're looking to make a coconut cake. It looks divine, but my friends don't like coconut :( 
2 sticks (226 g) butter, room temp
2 1/3 c (466 g) sugar
5 egg whites, room temp
2 teaspoons vanilla
3 c (375 g) flour
4 tsp baking powder
½ tsp salt
1 1/2 c (355 g) milk, warmed for 30 sec in microwave to bring to room temp
Red, orange, yellow, green, blue and purple GEL food coloring. Liquid will not be vibrant enough!

Preheat the oven to 350F degrees. Oil and line how ever many 9” cake pans you have (I have three and I just reused them). 

Sift together the flour, baking powder and salt. Set aside.

Cream the sugar and butter, then add the egg whites (I cracked them all into one bowl) and add them a little at a time. Add the vanilla and mix until fully incorporated. Then, alternating between wet and dry, add the milk and flour mixture in two parts.

Divide the batter amongst 6 bowls (I did it by weight. Weigh your mixing bowl before you begin adding ingredients and then subtract the weight of the bowl from the final measurement after the batter is completed. Divide that number by six and add that weight of batter to each bowl), and then whisk a fair amount of the appropriate food color into each bowl. Keep in mind that the color of the unbaked batter will be the color of the baked batter. Pour into the pans and bake for 15 minutes each. 

When you remove them from the oven, let them rest on the cooling rack, in the pan, for ten minutes. Then flip, cover, and stash them in the fridge to cool quickly. 

Lemony Swiss Meringue Buttercream
(Someday I will make a post, besides my pancakes or mint macarons, that doesn’t involve this recipe!)
I made this recipe twice today because I underestimated the amount of buttercream I would need/ I would recommend that you do the same because you would need a HUGE bowl to make this much buttercream at one time! Please click here for a step-by-step guide to making Swiss Meringue Buttercream and troubleshooting tips! 

To fill and crumb coat:
9 egg whites
1 ¾ c (350 g) sugar
4 sticks (532 g) of butter, room temp
2 tsp lemon extract

To frost:
5 egg whites
1 c (200 g) sugar
2 sticks (226 g) butter, room temp
1 tsp lemon extract

Cook the egg whites and sugar in a small saucepan over medium heat, whisking constantly, until the sugar is completely dissolved (test by rubbing some between your fingers. If it's completely smooth, it's done). Pour into another bowl (a stand mixer is preferable) and whip on high speed until room temp. Then, on a medium-slow speed, add the butter, waiting until each piece is completely incorporated before adding the next. After all the butter has been added, turn the mixer back to high speed and whip until it has come together, about five minutes. Add the extract, beat briefly and then use.

If the buttercream seems soupy after all of the butter is added and does not come together after whipping, refrigerate for 5 to 7 minutes and continue whipping until it becomes fluffy and workable.

Assembly
Stack the layers in your preferred order and fill and frost as you would any other cake. 

Once frosted, the cake can be left on the counter without any problems, but feel free to refrigerate it. Just be sure that the cake is at room temperature when serving or the frosting will be hard.


Good luck! The cake was delicious and so fun to make!