Here is the recipe from Whisk Kid's awesome cooking blog:Super Epic Rainbow Cake
I'm adding a disclaimer here: THERE IS A LOT OF FROSTING IN THIS CAKE. I think it's too much, personally, but I used a lot because I wanted the cake to be very striking visually. It is intentional.
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 butter, room temp
2 1/3 c sugar
5 egg whites, room temp
2 teaspoons vanilla
3 c flour
4 tsp baking powder
½ tsp salt
1 1/2 c milk, warmed for 30 sec in microwave to bring to room temp
Red, orange, yellow, green, blue and purple food coloring
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. 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!
To fill and crumb coat:
9 egg whites
1 ¾ c sugar
4 sticks of butter, room temp
2 tsp lemon extract
To frost:
5 egg whites
1 c sugar
2 sticks 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.
