Yellow Cake with Milk Chocolate Buttercream

The weather the past two days has been awful. In my opinion, 35 degree weather is bad enough, adding rain and wind is just downright miserable. But there is one good thing that comes out of awful winter weather: baking. The long walk to and from class a few times a day in this weather never fails to put me in a bad mood, but luckily a nice warm cake never fails to put me in a great mood.
I saw this cake and knew I had to make it since the subhead said it was the author's "go-to" birthday cake. I could see why after baking it, the cake is great. It was much more time-consuming than I had anticipated but if I had been making this cake for an occasion rather than just to have it around the apartment I think I wouldn't have minded nearly as much. This was definitely one of those cakes that took every bowl in the kitchen, big and small. The final result is a flavorful, light and moist 3 layer cake that beats any store bought cake by a mile. The frosting had a good flavor as well but I didn't love the consistency of it. I have made many buttercreams and I felt that this one was not nearly as good as half of the others but required considerably more work. Overall, the cake received rave review all around and I was the only one bothered by the frosting. It can also be made into cupcakes which I'm sure would turn out perfectly.

Yellow Cake with Milk Chocolate Buttercream
Recipe from Karen Demasco's The Craft of Baking

Ingredients 
2 tablespoons unbleached all-purpose flour
12 tablespoons (1 11/2) unsalted butter, very soft, plus extra for the pans
1 3/4 cup sugar
1 1/2 teaspoons pure vanilla extract
7 large egg yolks
3 cups cake flour
1 teaspoon kosher salt
3/4 teaspoon baking soda
1 cup plus 2 tablespoons sour cream
7 large egg whites

Buttercream
4 1/2 ounces milk chocolate, roughly chopped
12 ounces (3 sticks) unsalted butter at room temperature
3/4 cup egg whites (about 5 large egg whites)
3/4 cup sugar
3/4 teaspoon pure vanilla extract
3/4 teaspoon kosher salt


For the cake:

Butter the bottoms and sides of three 8-inch cake pans and line the bottoms of the pans with rounds of parchment paper. Butter the tops of the paper liners, and then dust the pans with the all-purpose flour, tapping off any excess.
Preheat the oven to 350 degrees.
In the bowl of an electric mixer fitted with the paddle attachment, mix the butter 1 1/2 cups sugar, and vanilla extract on medium speed, scraping down the sides of the bowl several times, until pale and fluffy, 5 minutes. Add the egg yolks, one at a time, letting each become incorporated into the batter before adding the next.
In a separate bowl, sift the cake flour, salt, baking powder, and baking soda. Reduce the mixer speed to low and alternate adding the flour mixture and the sour cream to the butter mixture, adding one third of each at a time and letting them fully mix in before adding the next. When all of the flour mixture and sour cram have been added, turn the mixer to medium-high speed and mix for about 2 minutes to fully incorporate the ingredients and help build the structure.
Scrape the batter into a large mixing bowl. Clean the bowl to the mixer well and, using the whisk attachment, whip the egg whites on low speed until frothy, about 5 minutes. Add the remaining 1/4 cup sugar and increase speed to medium high. Whip whites to soft peaks, then fold them into the batter in 3 additions.
Divide the batter between the three prepared cake pans and spread it out evenly with a spatula. Place pans on two baking sheets. Bake the cakes, rotating the pans and switching the cakes between the upper and lower racks of the oven halfway through, until they are lightly golden on top, gently bounce back when touched, and a cake tester inserted in the center of the cake comes out clean, 30 to 35 minutes.
Transfer the cake pans to a wire rack and let the cakes cool for 30 minutes. Then remove them from the pan and let them cool completely, at least 3 hours, before frosting.

For the buttercream:
Pour about 2 inches of water into a saucepan and bring it to a simmer. Place the chocolate in a heatproof bowl and set it over, but not touching, the simmering water. When the chocolate has melted, remove the bowl from the heat and whisk in 4 tablespoons of the butter. Set aside.
Combine the egg whites and the sugar in the bowl of an electric mixer, and set it over the same spot of simmering water. Whisking constantly so that the eggs don’t cook, heat the mixture until the sugar is completely dissolved, about 2 minutes. Transfer the bowl to the mixer fitted with the whisk attachment, and starting on low speed, beat the whites. When they become frothy and translucent, after about 3 minutes, increase the speed to medium. Beat until the whites become shiny and thick, about 2 minutes. Add the remaining 10 ounces (2 1/2 sticks) butter, 1 tablespoon at a time, without waiting for each to be absorbed. The buttercream will appear thin and broken. Add the chocolate mixture, vanilla and salt, and beat to combine, until it becomes shiny, smooth, and silky.
Using a serrated knife, trim the tops of the cake layers to make them level. Place one later on a cake plate and spread the top with 3/4 cup buttercream. Repeat with the second layer. Place the third layer on top. Using an offset spatula, spread the remaining buttercream over the entire cake, swirling to decorate.
The cake is best eaten the day it is assembled but can be kept at room temperature, loosely covered in plastic wrap, for up to 2 days.