Preheat the oven to 350°F.

In a medium bowl lightly combine the egg whites, 1/4 cup milk and vanilla.

In a large mixing bowl combine the dry ingredients and mix on low speed for 30 seconds to blend. Add the butter and remaining 3/4 cup milk. Mix on low speed until the dry ingredients are moistened. Increase to medium speed (high speed if using a hand mixer) and beat for 1-1/2 minutes to aerate and develop the cake's structure. Scrape down the sides. Gradually add the egg mixture in 3 batches, beating for 20 seconds after each addition to incorporate the ingredients and strengthen the structure. Scrape down the sides.

Scrape the batter into the prepared pans and smooth the surface with a spatula. The pans will be about 1/2 full. Bake 25 to 35 minutes or until a tester inserted near the center comes out clean and the cake springs back when pressed lightly in the center. The cakes should start to shrink from the sides of the pans only after removal from the oven.

Let the cakes cool in the pans on racks for 10 minutes. Loosen the sides with a small metal spatula and invert onto greased wire racks. To prevent splitting, reinvert so that the tops are up and cool completely before wrapping airtight.