Recipe: Chocolate Ice-Box Cake (sponge cake) (Aunt Sammy's Radio Recipes, 1931)

CHOCOLATE ICE-BOX CAKE

FOR THE CHOCOLATE CUSTARD MIXTURE:
2 squares unsweetened chocolate
1 pint milk
1/2 cup sugar
1/4 teaspoon salt
4 eggs
1/4 cup butter
1/4 teaspoon vanilla
FOR THE SPONGE CAKE:
4 eggs
1 cup sugar
3 tablespoons cold water
1 cup sifted soft-wheat flour
1 teaspoon baking powder
1/4 teaspoon salt
1/2 teaspoon vanilla
1/2 teaspoon lemon juice
powdered sugar or fill the center with whipped cream (for serving)

TO MAKE THE CUSTARD:
Melt the chocolate in a double boiler, add the milk, sugar, and salt. Beat the egg yolks, pour over them the hot mixture, return this combination to the double boiler, and stir constantly until the custard thickens. Remove from the heart, add the butter and vanilla, beat until well mixed, and fold this custard mixture into the stiffly beaten whites of the eggs. Chill before pouring over the sponge cake made according to the following recipe.

TO MAKE THE SPONGE CAKE:
Separate the egg yolks from the whites, and beat the yolks well. Gradually beat in the sugar, add the water, and continue the beating until the mixture is very thick and light.

Sift the dry ingredients together, and fold them into the egg and sugar mixture. Then fold in the stiffly beaten whites of the eggs, add the flavoring, and place in a slightly greased tube pan.

Bake in a in a very moderate oven (325 degrees F) for 45 to 50 minutes. Cool on wire rack.

TO ASSEMBLE THE CAKE:
When the cake is cool, split it crosswise into three sections, beginning at the top. Place the bottom section of the cake in the tube pan, and pour over it one-half of the chocolate custard mixture. Then put the next section in place, pour on the remainder of the custard, cover with the top layer, and chill for several hours.

WHEN READY TO SERVE:
Turn on to a platter and sprinkle with powdered sugar, or fill the center with whipped cream.

Source: Aunt Sammy's Radio Recipes, 1931