Strawberry Cupcake and Strawberry Frosting
2 3/4 cups all-purpose flour
1/2 cup cake flour (not self-rising)
1 tablespoon baking powder
1 teaspoon salt
8 ounces (2 sticks) unsalted butter, softened
2 1/4 cups sugar
3 large eggs plus 1 large egg white
1 cup whole milk
1 1/2 teaspoons pure vanilla extract
2 cups finely chopped strawberries, plus small strawberries for garnish
4 large egg whites, room temperature
1 1/4 cups sugar
3/4 pound (3 sticks) unsalted butter, softened, cut into small pieces
1 1/2 cups fresh strawberries, pureed
Make cupcakes as directed in Basic Cupcake How-To, using milk and vanilla for wet ingredients. Stir chopped strawberries into batter. Once cupcakes are cool, frost tops with strawberry buttercream. Frosted cupcakes will keep, covered and refrigerated, for up to 2 days. Top with a strawberry just before serving.
Place whites and sugar in a heatproof mixer bowl set over a pot of simmering water. Whisk until sugar dissolves and mixture registers 160 degrees on a candy thermometer.
Remove from heat, and attach bowl to a mixer. Whisk on medium speed for 5 minutes. Increase speed to medium-high, and whisk until stiff, glossy peaks form, about 6 minutes. Reduce speed to medium, and add butter, 1 piece at a time, whisking well after each addition.
Switch to a paddle attachment. With mixer on low, add strawberry puree, and beat until smooth, 3 to 5 minutes. Use immediately, or cover, and refrigerate for up to 3 days. (Bring to room temperature, and beat on low speed until smooth before using.)