Yield: 34 cupcakes
For the cupcakes:
2¼ cups all-purpose flour
½ cup cake flour
1 tbsp. baking powder
1 tsp. salt
2 sticks (1 cup) unsalted butter, at room temperature
2¼ cups sugar
1½ tsp. vanilla extract
3 large eggs plus 1 large egg white
1 cup milk
2½ cups finely chopped fresh strawberries*
For the frosting:
1½ cups fresh strawberries (8 oz.), rinsed, hulled and coarsely chopped*
4 large egg whites
1¼ cups sugar
3 sticks (1½ cups) unsalted butter, at room temperature
Additional fresh strawberries*
To make the cupcakes, preheat the oven to 350˚ F. Line cupcake pans with paper liners. In a medium bowl, combine the all-purpose flour, cake flour, baking powder and salt; whisk to blend.
In the bowl of an electric mixer, combine the butter, sugar and vanilla. Beat on medium-high speed until light and fluffy, about 3 minutes. Beat in the eggs and egg white one at a time, mixing well after each addition and scraping down the sides of the bowl as needed. With the mixer on low speed, add the flour mixture in two additions alternating with the milk, mixing each addition just until incorporated. Gently fold in the chopped strawberries with a spatula.
Divide the batter between the paper liners, filling each about ¾-full. Bake until light golden and a toothpick inserted in the center comes out clean, about 25-28 minutes, rotating the pans halfway through baking. Allow to cool in the pans a few minutes, then transfer to a wire rack to cool completely.
To make the frosting, place the strawberries in a food processor or blender. Puree until completely smooth. Combine the egg whites and sugar in a heatproof bowl set over a pot of simmering water. Heat, whisking frequently, until the mixture reaches 160° F and the sugar has dissolved.
Transfer the mixture to the bowl of a stand mixer** fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form and the mixture has cooled to room temperature, about 8 minutes. (The bowl should be cool to the touch.)
Reduce the speed to medium and add the butter, 2 tablespoons at a time, adding more once each addition has been incorporated. If the frosting looks soupy or curdled, continue to beat on medium-high speed until thick and smooth again, about 3-5 minutes more (or longer – don’t worry, it will come together!) Blend in the strawberry puree until smooth and completely incorporated, scraping down the sides of the bowl as needed.
Fill a pastry bag fitted with a decorative tip with the frosting. (I used a large, unlabeled star tip to frost these cupcakes.)Frost cooled cupcakes as desired, and garnish with fresh berries or berry slices.