A three-egg version.
From a box sold in Quincy, Massachusetts.
Sponge Cake
3 eggs
1 cup sugar
1/4 cup hot water
1 scant cup sifted flour
1 tsp. baking powder
1/4 tsp. salt
1 tsp. vanilla
Beat egg whites in bowl.
Beat egg yolks; add sugar. Beat well. Add sifted dry ingredients, alternately with hot water, and vanilla. Fold in beaten egg whites.
Let set in oven a few seconds after turning off heat. Cook in angel tin. Oven temperature 350 deg.