Sift the flour and baking powder together in a medium size bowl.
In another bowl, beat the egg whites with the salt until they hold stiff peaks. Set aside.
Combine the the dry ingredients with the butter mixture, add the milk. Gently fold in the egg whites to lighten the mixture. Mix just until blended.
Divide the batter between the pans and bake until the cakes pull away from the sides of the pan, about 25 minutes, transfer the cakes to a rack to cool.
Sandwich the layers with frosting, then spread on the top and sides.
Chocolate Sour Cream Frosting
5 1-ounce squares semisweet chocolate
1/2 cup sour cream
1/8 teaspoon salt
Melt the chocolate squares. Let chocolate cool down then stir in the sour cream and salt. :)