Preheat oven to 350 degrees. Prepare muffins tins. This recipe yields 24-28 cupcakes.
In the bowl of stand mixer with paddle attachment, cream together butter, baking powder, sugar, salt, and extracts until light and fluffy, about 5 minutes. (be sure to stop half way and scrape down sides)
With the mixer on the lowest speed, carefully add in egg whites, one at a time, beating well after each addition. (scrape down sides as necessary)
With mixer still on low, add in 1/3 of the flour into the creamed mixture, then half the milk, another third of the flour, the remaining milk, and then the remaining flour. (scrape down sides as necessary)
Using a 1/4 cup ice cream scoop or a 1/4 measuring cup, fill muffin tin.
Bake for 16-22 minutes, or just until cupcakes start to brown and the center springs back when touched. You can also insert a toothpick into the center of the cupcake, and if removed mostly clean, cupcakes are done. Make sure to not brown cupcakes as they are better when slightly less done.
Remove cupcakes from oven and cool in pan for up to five minutes, then invert onto wire rack. Cool completely before frosting.