1 c. milk
6 egg whites
2 t. vanilla
2 1/2 c. cake flour
3/4 c. sugar
1 T. baking powder
1 t. salt
12 t. butter (soft but cool)

Preheat oven to 350. In a medium bowl, whisk until combined the milk, egg whites, and vanilla. In a stand mixer, combine the flour, sugar, BP, and salt. While the mixer is running on low, add the butter a tablespoon at a time. Let the mixer continue until there are no visible chunks. Add all but a half cup of the milk mixture. Beat on medium for about 90 seconds until light and fluffy. Scrape the sides and add the remaining milk mixture. Combine on low, then take up to medium for another 30-60 seconds.