Preheat oven to 350 degrees. Prepare three 8" cake pans with pam and parchment.
In a medium bowl combine the egg whites chopped rosemary and vanilla set aside.
In the bowl of an electric mixer fitted with the paddle attachment, combine flour, sugar, baking powder, and salt together on low speed for 30 seconds.
Add the butter, and mix on a low speed until just combined.
Add milk and mix until just combined. Increase to medium speed and mix for 1-2 minutes.
Scrape the sides of the bowl and begin to add the egg mixture in 2 separate batches, beat on medium speed until it is just combined.
Divide the batter between the three cake pans.
Bake for 25-30 minutes or until a toothpick comes out clean.
Let cool on racks until cooled completely.