Cupcakes 2 1/4 cups all-purpose flour 1/2 cup cake flour 1 tablespoon baking powder 1 teaspoon salt 1 cup (2 sticks) unsalted butter, at room temperature 2 1/4 cups sugar 1 1/2 teaspoons vanilla extract
3 large eggs plus 1 large egg white, at room temperature 1 cup milk, at room temperature 2 cups finely chopped fresh strawberries
Frosting 1 1/2 cups fresh strawberries (8 oz.), rinsed, hulled and coarsely chopped 4 large egg whites 1 1/4 cups sugar 1 1/2 cups (3 sticks) unsalted butter, cut into tablespoons, at room temperature
To make the cupcakes: Preheat oven to 350 F. Line cupcake pans with paper liners.
In a medium bowl, whisk together the all-purpose flour, cake flour, baking powder and salt.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, sugar and vanilla on medium-high speed until light and fluffy, about 3-4 minutes. Add the eggs and the egg white, one at a time, beating well after each addition and stopping to scrape the sides of the bowl as necessary. With the mixer on low speed, add the flour mixture in two additions alternately with the milk, mixing only until incorporated. Gently fold in the chopped strawberries with a rubber spatula.
Fill each well of the cupcake pans about 3/4-full with the batter. Bake for 25-30 minutes, or until the cupcakes are golden and a toothpick inserted in the center comes out clean. Remove the cupcake pans to a wire rack to cool for 5-10 minutes, then remove the cupcakes from the pans to the rack to cool completely.
To make the frosting: Puree the strawberries in your food processor until completely smooth. Add the egg whites and sugar to the bowl of your stand mixer (or any heatproof bowl) and set it over a pan of simmering water. Heat, whisking constantly, until the sugar has dissolved – you can test with your fingertips, if the mixture feels grainy, it’s not ready yet.
Attach the bowl to your stand mixer (or transfer the mixture to the bowl of a stand mixer if you used a separate bowl) fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form and the mixture has cooled to room temperature, about 10 minutes. (The bowl will be cool to the touch.)
Reduce the mixer to medium-low speed and add the butter, 2 tablespoons at a time. Let each addition incorporate before adding the next. (The frosting may look soupy or curdled once you add the butter – just keep beating and it will come together.) Scrape down the sides of the bowl with a rubber spatula, then add the strawberry puree to the bowl. Beat until combined – the mixture will probably look curdled again when you add the strawberries, keep beating!)
Pipe the buttercream onto the cupcakes (I used a large star tip), and garnish with extra strawberries, if desired.
Yields 34 cupcakes