- 3 1/2 sticks unsalted butter, room temperature, plus more for pans and parchment
- 6 1/2 cups sifted cake flour (not self-rising), plus more for pans and parchment
- 3 tablespoons baking powder
- 2 1/4 cups whole milk
- 2 tablespoons pure vanilla extract
- 2 1/2 cups sugar
- 10 large egg whites
- Gel-paste food coloring (<a href="http://nycake.com" target=_"blank">nycake.com</a>)
- <a href="/recipe/swiss-meringue-buttercream-recipe">Swiss Meringue Buttercream</a>
- Preheat oven to 350 degrees. Butter five 8-inch round cake pans, and line with parchment (you may need to bake in batches). Butter parchment, and dust with flour, tapping out excess. Sift flour, baking powder, and 1/2 teaspoon salt into a large bowl. Combine milk and vanilla. Beat butter with a mixer on medium speed until very smooth. With machine running, gradually add sugar, and beat until pale and fluffy, about 3 minutes.
- Reduce speed to low, and add flour mixture in 3 additions, alternating with milk mixture, beginning and ending with flour. Beat until just combined; do not overmix.
- Beat egg whites in a clean mixer bowl on medium speed until stiff (but not dry) peaks form, about 3 minutes. Gently fold egg-white mixture into batter in 3 additions.
- Divide batter among 5 bowls, and tint each with food coloring to create different pastel shades. Spread each into a prepared pan. Bake until a toothpick inserted into the centers comes out clean, 18 to 20 minutes. Let cool completely in pans on wire racks.
- Loosen edges of cake with a small metal spatula or paring knife; invert onto racks. Discard parchment. Reinvert cakes, top side up. Let cool completely.
- Trim top of each cake to make surface even. Spread 1 cup buttercream onto top of 1 cake. Top with another cake. Repeat, spreading 1 cup buttercream between each layer. Frost cake with 1 1/2 cups buttercream. Refrigerate for 30 minutes. Frost cake with 2 cups buttercream.
To make ahead, unfrosted cakes can be stored at room temperature for up to 2 days. Refrigerate for up to 2 days to store.