I’m always intrigued by old cake recipes that have titles which emphasize the use, or non-use, of a specific ingredient. For example, I recently came across a recipe for One Egg Chocolate Cake. Why was the number of eggs stated in the title? Were eggs really expensive back then? . . . or maybe the recipe was aimed at families that raised chickens, and the chickens didn’t lay many eggs during the winter so cooks were looking for recipes that used few eggs. . . or. . . ?
This recipe made a 9-inch square cake, and was very tasty. I never missed any reduction in eggs.
Here’s the original recipe:

I followed the recipe directions and grated the chocolate, then melted it by adding a little hot water and stirring. I was surprised how well this process melted the chocolate – though think that the baking chocolate probably could be melted in the microwave to avoid the extra effort of grating the chocolate.
Here’s the recipe updated for modern cooks:
One Egg Chocolate Cake
1 cup sugar
1 egg yolk
1/4 cup butter, softened
1/2 cup grated baking chocolate (about ounces of chocolate)
2 tablespoons hot water
approximately 3/4 cup milk
1 tablespoon vinegar or lemon juice (I used vinegar.)
1 teaspoon baking soda
1 teaspoon vanilla
1 1/2 cups flour
Preheat oven to 350° F. Put the grated baking chocolate in a measuring cup, then add hot water and stir until the chocolate is melted. Stir in vinegar and enough milk to make 1 cup. Set aside for at least 2 minutes.
Put sugar and egg yolk in a mixing bowl, stir to combine. Add butter, milk and chocolate mixture, baking soda, vanilla, and flour; beat until smooth. Put in a greased and floured 9-inch square pan. Bake until a wooden pick comes out clean (approximately 35 minutes). Frost if desired