Happy birthday to me!!! Yes, I made my own birthday cake. I am now 28 years old and making my own cake. I could have asked my husband to make it for me, but I’m not sure that would have worked out too well. And my pastry chef sister lives across the country in Seattle, so that option was out. So I guess I figured I could just make it myself. In fact, two months ago, my friend (Gina Masri…thanks!) sent me a link to this Martha Stewart recipe and right then and there, I knew that I wanted to make it for my own birthday. I’ve been counting down to this moment and here it is! I get to have a fun birthday with presents and family (gotta love my priorities) AND I get to make a crazy rainbow cake. Does life get any better?!?
Rainbow Layer Cake Ingredients
3 cups all-purpose flour
4 tsp baking powder
1/2 tsp salt
2 sticks (1 cup) unsalted margarine, room temperature
2 1/3 cups sugar
5 egg whites, room temperature
2 tsp vanilla extract
1 1/2 cups soy milk, room temperature
red, orange, yellow, green, blue and purple gel food coloring
*for the frosting, you can make homemade buttercream (he recipe is below but mine didn’t work out too well) or use 3 containers of pre-made vanilla frosting, such as Duncan Hines
I preheated the two ovens in my kitchen to 350 degrees. If you only have one oven, just heat that one up. I prepared six 9-inch-round foil pans with vegetable spray, then lined the bottom of each with parchment paper and sprayed again.
In a large bowl, I whisked together the flour, baking powder and salt. In an electric mixer, I creamed together the margarine and sugar. Slowly, I added the egg whites and mixed until well combined.
Now came the really fun part! I divided the batter evenly between six medium bowls. Each bowl contained around 1 cup of batter. I used Wilton Icing Colors to dye the cakes. You can use any brand of gel food coloring, but I think the Wilton concentrated gels give a vibrant color without thinning the batter.
I wore gloves while I dyed the batter so I wouldn’t get any color on my hands. I suggest you do the same, unless you want multi-colored fingers! I added 1/8 tsp. of each color to its designated bowl and whisked away. I added a bit more for the red batter, since I didn’t think the color was bright enough. Between each bowl, I washed the whisk so the colors wouldn’t combine.
I transferred each color to the prepared cake pans then moved those pans in to the ovens. If you don’t have room in your oven for all six pans, you can bake them in batches. The cakes baked for only 15 minutes, so if you need to work in batches, it won’t take too long.
While the cakes were cooling, I attempted to make the frosting that Martha Stewart recommended: Lemony Swiss Meringue Buttercream. It didn’t work out too well, so I’ll just give you the basics. I decided not to remake the frosting because it called for 6 sticks of butter and I wasn’t ready to actually eat that much fat!
So here it goes: I cooked 9 egg whites and 1 3/4 cups of sugar in a small saucepan over medium heat, whisking constantly until the sugar was dissolved. I transferred to an electric mixer and whisked on high until the mixture was room temperature. I think this is where I made my mistake. The directions did not say how long to whisk so I wasn’t sure how fluffy the mixture should have been. I just had to guess…and I think I guessed wrong. With the mixer on medium-low, I added the pieces of margarine (4 sticks, room temperature, cut into small pieces), one piece at a time, mixing well after each addition. That took a while, which is another reason I didn’t want to remake the frosting and just “settled” on delicious Duncan Hines.
Once all of the margarine was added, I removed the whisk attachment and switched to the paddle. I increased the speed to high and beat the mixture until the buttercream was supposed to come together, around 5 minutes. Needless to say, my mixture did not become a thick buttercream!
By the time I was done messing up the lemon buttercream, the cakes were completely cool. Martha Stewart suggests trimming the tops of the cakes to make them level, but I skipped this step since my cakes were fairly even. You are welcome to trim the tops using a serrated knife, if you want! I placed four strips of parchment paper around the perimeter of a 10 inch cake circle, then placed the purple layer in the center. I spread 1 cup of frosting over the first layer with a spatula so it extended just beyond the edges of the cake.
I placed the remaining red layer on top, bottom-side up.
I swept away any loose crumbs then covered the top and side with a thin layer of frosting with a spatula, also using any of the excess frosting visible between the layers. I refrigerated the cake for 30 minutes, until it set.