Funfetti cake with funfetti icing

One of my sisters is going on a trip.  A looooong trip.  And she actually made a baking request before she leaves.  I say "actually" because my sisters generally don't like sweets (I know, they're not normal), and with the exception of Oreos, I don't think my sister has ever asked me for dessert.  So when her request came in for a funfetti cake (...correction, a funfetti cake WITH funfetti icing), I know I had to oblige.  Of course, besides sprinkles in the cake, I don't know what makes a cake "funfetti."  From my limited knowledge of boxed cake mixes, it appears to be a vanilla yellow cake with....colorful sprinkles.  So that's what I set out to make.  I used my regular yellow cake, upped the vanilla a little bit, and threw in a giant handful TON of colorful sprinkles.

Funfetti icing proved to be a little more difficult.  Simply because she wanted vanilla funfetti icing (which I guess makes sense, right?), and I don't have a go-to vanilla icing.  Ultimately, I decided on a vanilla buttercream with....yup....a giant handful TON of rainbow sprinkles!

Funfetti Cake
Based on a recipe for yellow cake from one of my favorite cooking blogs ever, Smitten Kitchen.
This recipe gave me two very nice 9 round layers PLUS 11 mini cupcakes.  I usually half the recipe when making cupcakes or mini cupcakes because this makes a lot of batter.

Ingredients:

4 cups plus 2 Tablespoons cake flour (not self-rising)
2 teaspoons baking powder
1 1/2 teaspoons baking soda
1 teaspoon table salt
2 sticks unsalted butter, softened
2 cups sugar
1 Tablespoon pure vanilla extract (I upped the vanilla from the original recipe)
4 large eggs, at room temperature
2 cups buttermilk, well-shaken
1/2 cup rainbow sprinkles, plus another small handful for good measure

Directions:

Preheat oven to 350°F.
Butter two 9-inch round cake pans and line with circles of parchment paper, then butter parchment. (Alternately, you can use a cooking spray, either with just butter or butter and flour to speed this process up -- I used Pam for baking....it's wonderful, and my cakes popped out of the pan perfectly!)

Sift together flour, baking powder, baking soda, and salt in a medium bowl.
In a large mixing bowl, beat butter and sugar in a large bowl with an electric mixer at medium speed until pale and fluffy, then beat in vanilla.
Add eggs 1 at a time, beating well and scraping down the bowl after each addition.
At low speed, beat in buttermilk until just combined (mixture will look curdled).
Add flour mixture in three batches, mixing until each addition is just incorporated.
Add sprinkles.

Spread batter evenly in cake pan, then rap pan on counter several times to eliminate air bubbles.
Bake until golden and a wooden pick inserted in center of cake comes out clean, 35 to 40 minutes.
Cool in pan on a rack 10 minutes, then run a knife around edge of pan.
Invert onto rack and discard parchment, then cool completely, about 1 hour.

Funfetti Icing

Ingredients:

6 egg whites
1 1/2 cups granulated sugar
1 pound unsalted butter, cubed and at room temperature
vanilla extract, to taste, I used about 2 tsp
colored sprinkles

Directions:

Whisk the egg whites and sugar together in the bowl of an electric mixer.
Place over a double boiler and whist constantly until the mixture is hot to the touch and all of the sugar has dissolved
Whip on high with the whisk attachement of an electric mixer until thick, fluffy, and cool to the touch.
Add vanilla.
Switch to paddle attachment.
Begin adding the butter, a few tablestooms at a time, until completely incorporated.
Add sprinkles, a little at a time, until desired amount of sprinkles have been added.