Chocolate Cake

From 1922:

Quarter pound of butter, ¼ lb sugar, ¼ lb. self-raising flour, 2 eggs, 2oz. grated chocolate, 1 teaspoonful of cocoa. Stir the butter to a cream, then add the sugar; beat up the eggs with a few drops of essence of vanilla; stir into butter and sugar, then sift the flour in lightly (having been previously warmed); then mix the chocolate to a smooth paste with warm water, adding the cocoa to darken it. Stir this into the cake, which must be quite smooth. Bake for one hour in a rather quick oven.