White Mountain Layer Cake with Buttercream Frosting

Ingredients

Cake

4 cups (16 oz.) bleached cake flour such as Swans Down

2 sticks (8 oz.) unsalted butter, pliable but cool—about 65°F

2⁄3 cup (4 oz.) virgin coconut oil, solid but cream–about 70°F

2 1⁄4 cups (16 oz.) sugar

2 1⁄2 tsp. baking powder

1 tsp. baking soda

3⁄4 tsp. Diamond Crystal kosher salt (half as much if iodized)

1 cup (8 1/2 oz.) egg whites (from 8 large eggs), brought to about 70°F

2 tbsp. (1 oz.) vanilla extract

1 tsp. almond extract

2 cups (16 oz.) cultured low-fat buttermilk, brought to about 70°F

Frosting

4 large eggs

1 cup granulated sugar

2 teaspoons vanilla extract

pinch table salt

1 pound (454 grams) unsalted butter (4 sticks), softened, each stick cut into quarters

Instructions

FOR THE CAKE:

1. Adjust an oven rack to lower-middle position and preheat to 325°F. Line three 8-by-3-inch anodized aluminum cake pans with parchment and grease with pan spray; if you don’t have three pans, the remaining batter can be held at room temperature for up to 3 hours. (The cakes will brown more and rise less in 2-inch pans.) Sift the flour (if using cup measures, spoon into the cups and level with a knife before sifting) and set aside. Combine butter, coconut oil, sugar, baking powder, baking soda, and salt in the bowl of a stand mixer fitted with a paddle attachment. Mix on low speed to moisten, then increase to medium and cream until fluffy and light, about 5 minutes, pausing to scrape the bowl and beater halfway through. With the mixer running, add the egg whites one at a time, followed by vanilla and almond extracts.Reduce speed to low and sprinkle in one-third of the flour, followed by one-third of the buttermilk. Alternate between the two, allowing each addition to be roughly incorporated before adding the next. Once smooth, fold with a flexible spatula to ensure it’s well mixed from the bottom up. Divide among the prepared cake pans, about 22 ounces each.

2. Bake until the cakes are firm but pale, browned only around the very edges, about 40 minutes (or 210°F). A toothpick inserted into the center will emerge with a few crumbs still attached, and your fingertip will leave a slight indentation in the puffy crust. Cool until no trace of warmth remains, about 90 minutes.

FOR THE BUTTER CREAM:

3. Combine eggs, sugar, vanilla, and salt in bowl of standing mixer; place bowl over pan of simmering water. Whisking gently but constantly, heat mixture until thin and foamy and registers 160 degrees on instant-read thermometer.

4. Beat egg mixture on medium-high speed with whisk attachment until light, airy, and cooled to room temperature, about 5 minutes. Reduce speed to medium and add butter, one piece at a time. (After adding half the butter, buttercream may look curdled; it will smooth with additional butter.) Once all butter is added, increase speed to high and beat 1 minute until light, fluffy, and thoroughly combined. (Can be covered and refrigerated up to 5 days.)

4. Loosen the cakes from their pans with a knife. Invert onto a wire rack, peel off the parchment, and reinvert. Crumb-coat and frost with butter cream. Serve immediately or store under a cake dome or an inverted pot; the frosted cake will keep for up to 24 hours at room temperature.