Sunday, February 10, 2013

Rainbow Birthday Cake


Birthdays are pretty much my favorite days ever. Cards, cakes and candles are really exciting to me, and I love memorizing the dates of people's birthdays. If I know you, I most likely know your birthday date as well. I also have a book specifically for birthday dates, just in case I need a refresher.

And, as you might have guessed, this cake is a birthday cake because today is Jessica's birthday!

Of course, I had to make her cake, so after looking around, I decided on this rainbow cake. I made it about two years ago for another birthday, and it was amazing, so I thought that it would be the perfect thing to make for this weekend.



Not only is this cake visually pleasing, but it's delicious as well. It all starts with a moist, white cake, colored with six colors of the rainbow. Then, there's the smooth and silky swiss meringue buttercream.



I didn't tell Jessica that the cake was rainbow, so when she cut into it, she was surprised by the six layers and colors. It's a pleasant surprise!


I also went a little crazy with the gold sprinkles on top, but I thought it was the right and final touch to finish the cake.



Happy birthday Jessica!!


Rainbow Birthday Cake with Swiss Meringue Buttercream
cake from Whisk Kid, buttercream from Sweetapolita
makes one giant 9-inch cake

for the cake:
1 cup unsalted butter, room temperature 
2 1/3 cups (426 g) granulated sugar
5 large, fresh egg whites, room temperature 
2 teaspoons pure vanilla extract
3 cups (426 g) all-purpose flour
4 teaspoons baking powder
1/2 teaspoon salt
1 1/2 cups milk, room temperature 
red, orange, yellow, green, blue and purple gel food coloring 

for the filling and crumb coat:
10 large, fresh egg whites (300 g) 
2 1/2 cups (500 g) granulated sugar
3 cups (680 g) unsalted butter, cut into tablespoons, room temperature 
1 tablespoon + 1 teaspoon pure vanilla extract
pinch of salt 

for the final frosting:
5 large, fresh egg whites (150 g) 
1 1/4 cups (250 f) granulated sugar
1 1/2 cups (340 g) unsalted butter, cut into tablespoons, room temperature 
1 tablespoon pure vanilla extract
pinch of salt 

To make the cake, preheat oven to 350F and grease however many 9-inch round cake pans you have (I reused my two three times to achieve the six layers).
Weigh the bowl of an electric mixer and write down or remember how much it weighs. You will need this later when you divide the batter between the cake pans.
In a medium bowl, sift together the flour, baking powder salt and set aside.
In the bowl of an electric mixer, cream together the butter and sugar. Add the egg whites, one at a time, waiting until each is incorporated before adding the next. Beat in the vanilla until combined. Add the dry ingredients and milk in two parts, alternating between the two.
Weigh your electric mixing bowl with the batter and subtract the weight of your empty mixing bowl. Then, divide this number by six. Gather six empty, small bowls and weigh the amount of batter you calculated that will be in each pan into the small bowls. Then, add the six food colors to each separate bowl of cake batter. Whatever color your batter is at this point will be the color it is once it comes out of the oven.
Scoop the colored batter into separate greased 9-inch cake pans and bake 15 minutes each. Then, allow to cool on a wire rack for 10 minutes before inventing and allowing to cool completely.
To make the buttercream for the filling and crumb coat, wash a bowl of an electric mixer and make sure it is completely clean and rid of any grease, oil or other junk. Combine the egg whites and sugar in the mixing bowl and place over a small pot filled with about an inch of water over medium heat. Whisking constantly, cook until the sugar has dissolved and the egg whites are hot. Take off heat and place the bowl in your electric mixer fitted with a whisk attachment.
Whip the warmed sugar and egg whites until glossy, thick and the bowl feels neutral, not warm. This may take about 10 minutes. Switch to the paddle attachment and add the tablespoon chunks of butter, one at a time, waiting until each is incorporated before adding the next, until a smooth, silky texture is achieved. It is okay if it curdles, just keep whipping. If your mixture seems too soupy or warm after you add the butter, just stick in the refrigerator for about 15 minutes before whipping fully. Beat in the vanilla and salt until combined.
Use this icing to fill and crumb coat your six layer cake. Stick in the refrigerator while you make the final frosting.
To make the final buttercream, repeat the instructions for the filling and crumb coat, but with the halved measurements provided. Use to frost the outer layer of your cake. Store in an airtight container in the refrigerator and serve at room temperature. 


  1. Hi Elizabeth, your rainbow cake look so beautiful. Too pretty to be eaten. The cream look very nice , yum yum.

    Have a nice week ahead, regards.


  2. Absolutely beautiful!

  3. I am home sick right now and all I want is a big piece of this pretty cake!

  4. I hope you feel better! I also wish I could send a piece of cake your way!!

  5. Your layers are perfect!! Your cake looks absolutely beautiful!! =)

    Ergo - Blog

  6. My husband just looked over and said: That's a very pretty cake, and it's perfectly frosted. Aaaaaand now he wants cake.



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