3 cups cake flour 1 tablespoon baking powder 1/2 teaspoon salt 2/3 teaspoon unsalted butter, softened 1 3/4 cup sugar 1 1/2 cup milk 2 teaspoons vanilla extract 4 large egg whites 1 cup semisweet chocolate chips
Preheat oven to 350 degrees F. Grease and lightly flour two 9 x 2-inch round cake pans. Line the bottoms with waxed paper.
In a medium bowl, sift together the flour, baking powder, and salt. Set aside.
In a large bowl, on the medium speed of an electric mixer, cream the butter and sugar until fluffy, about 3 minutes. Mix the milk and the vanilla extract together.
Add the dry ingredients in three parts, alternating with the milk and the vanilla extract mixture, beating well after each addition.
In a separate bowl, on the high speed of an electric mixer, beat the egg whites until soft peaks form. Gently fold into batter, making sure no streaks of white are showing. Then gently stir in the chocolate chips.
Divide the batter between the prepared pans. Bake for 25 to 30 minutes or until a cake tester inserted into the center of the cake comes out clean. Let cake cool in pans for 10 minutes. Remove from pans and cool completely on wire rack.
When cake has cooled, ice between the layers, then ice top and sides of cake.