From 1912:

Half a cup each of sweet milk and of granulated sugar, two squares of chocolate. Boil these until they are thick and smooth, and set aside to cool while you prepare the batter.
One cup of granulated sugar, half a cup of butter, and the same quantity of sour milk, in which dissolve a scant teaspoonful of soda, two eggs (saving the white of one for frosting), two cups of sifted flour and a teaspoonful of vanilla. After mixing all the rest of the ingredients, beat in the chocolate mixture last of all. Put the layers together with boiled icing.
A fine cake and economical.