Steamed Chocolate Pudding

One pint of milk, three stale

From 1922:

One pint of milk, three stale sponge cakes, two tablespoonfuls of sugar, three ounces chocolate (unsweetened), three eggs, vanilla flavoring. Grate the chocolate and stir it with the sugar into the boiling milk until dissolved. Cool a little and add the beaten yolks, crumbled sponge cakes, and lastly the whites, beaten stiff. Pour into a buttered mould and steam two hours.