1. Preheat oven to 350F.

2. Butter and lightly flour two 8" round cake pans.

3. Cream the butter until softened and slowly add the sugar, beating until light. Add the egg yolks and vanilla and beat to blend well.

4. Sift the flour, baking powder, and salt onto a piece of waxed paper. Alternately blend the dry ingredients and the milk into the butter mixture in three stages. Beat until smooth.

5. In a separate bowl, beat the egg whites until stiff but not dry. Stir a third of the whites into the cake batter and gently fold in the remaining. Spoon into cake pans.

6. Bake for 30-35 minutes, or until a straw inserted in the center of the cake comes out dry. Cool in pans for 5 minutes before turning out onto racks.