Cream the snowdrift and sugar thoroughly and add the flavoring. Measure sifted flour, add salt and baking powder and sift several times. Add alternately with the milk to the creamed mixture. Beat smooth and fold in the stiffly beaten egg whites. Pour into two greased nine-inch layer cake pans. Bake in a moderate oven 375 degrees F. for twenty-five minutes. Put together with Lady Baltimore Filling.