- Preheat oven to 350 degrees F (175 degrees C). Grease and flour three 9-inch round pans.
- Beat butter and 1 cup of sugar with an electric mixer in a large bowl until light and fluffy. The mixture should be noticeably lighter in color.
- In a separate bowl, beat egg yolks well, then add to butter mixture.
- Sift together flour and baking powder. Add alternately with the milk to the butter-sugar mixture. Beat well. Add vanilla.
- Beat egg whites until stiff but not dry. Add 1 cup sugar to the egg whites. Fold into cake batter.
- Divide evenly into three prepared 9 inch round pans. Bake at 350 degrees F (175 degrees C) for 25 minutes.