For the Cupcakes

1. Preheat to 350ºF and line two cupcake tins with cupcake liners.
2. Sift the dry ingredients together and set aside.
3. In your mixer’s bowl, cream together butter, sugar, and vanilla on medium-high speed until light and fluffy.
4. Add the eggs and egg white, one at a time, mixing in between each addition. Scrape down the sides of the bowl as needed.
5. Alternate adding the flour mixture and the milk over low speed, beginning and ending with the flour until well combined.
6. Fold in chopped strawberries by hand.
7. Transfer the batter to the prepared cupcake pan. Fill each cupcake liner 1/2 – 3/4 of the way full.
8. Bake at 350ºF for 20-25 minutes, until a toothpick inserted into the center of a cupcake comes out clean.
9. Cool completely on a wire rack before frosting.

For the Swiss Meringue Buttercream

1. Puree the strawberries in a blender or processor.
2. Combine the egg whites and sugar in a double boiler (see note). Whisk continuously until the sugar has dissolved into the egg whites and the mixture is warm. It should feel smooth, and not grainy when rubbed between your fingers.
3. Starting slowly, beat the egg white and sugar mixture using the whisk attachment of your stand mixer. Gradually increase the speed to medium-high until stiff peaks form, and the mixture is fluffy and glossy. After about 8-10 minutes, the mixture will have cooled.
4. With the paddle attachment fitted onto the mixer, add the butter 3 Tablespoons at a time, mixing well in between each addition. Scrape down the sides of the bowl when all the butter is combined and smooth. Then, reduce the speed to low and continue to mix for about 2 minutes.
5. Add pureed strawberries and beat the frosting on medium until everything is well combined, then stir with a spoon or spatula until smooth.