2 3/4 c. all-purpose flour
1/2 c. cake flour
1 Tbsp. baking powder
1 tsp. salt
2 sticks butter, softened
2 1/4 c. sugar
3 large eggs
1 egg white
1 c. buttermilk
1 1/2 tsp. vanilla extract
1 lb. strawberries, pureed A few drops of red food coloring (optional; I understand it's kind of a hot topic, but they turn out a bit gray inside if you don't use it...)
Double recipe of Perfect Cupcake Frosting and Filling
Preheat oven to 350. Line a METAL muffin pan with paper liners--you absolutely must use a metal pan in this recipe to give them as much help as they can get rising. Whisk flour, cake flour, baking powder, and salt in a medium bowl. Cream butter and sugar with a mixer until light and fluffy (about 3 minutes). Add eggs and egg white, one at a time, beating after every addition.
Reduce speed to low. Combine buttermilk and vanilla together and set aside. Add dry ingredients to creamed mixture in 3 additions, alternating with the milk mixture; end with the dry ingredients. If desired, add a few drops of red food coloring until a pretty pink color is reached. Scrape the sides of the bowl to ensure everything has been mixed in. Divide batter among muffin cups (about 30), filling them almost all the way to the top.
Bake cupcakes until a knife inserted into the centers comes out clean, about 22-25 minutes. Allow to cool in muffin tins. Top with a swirl of frosting (just cut a generous hole off the corner of a Ziploc or disposable decorating bag and swirl around the cupcake).