Cream sugar and butter together. Sift the flour, baking powder and cornstarch together. Alternate adding these to creamed mixture along with milk. Beat until very smooth. Add vanilla and then fold in egg whites that have been beaten until stiff. Bake in 2 greased and floured 8" round cake pans for 25 to 30 minutes in a 350 degree oven. Frost with Boiled White Icing.
BOILED WHITE ICING
2 cups sugar
2/3 cup boiling water
1/8 tsp. cream of tartar
2 egg whites, stiffly beaten
1 tsp. vanilla
In saucepan, combine, sugar, water, and cream of tartar, stirring until sugar is dissolved. Boil without stirring until syrup begins to spin a thread (235 degrees). Remove 3 Tbs. of the sugar mixture, adding one at a time to the egg whites. Cook syrup until it is really spinning a thread (240 degrees). Add all of syrup very slowly to egg whites, beating until as thick as desired. Stir in vanilla.