My mom made this cake all the time when I was growing up. Somehow the cookbook was lost, but I recently found a copy of the 1967 Southern Living Dessert Cookbook. This is actually called the Five-Minute Chocolate Cake and Instant Fudge Frosting. The beauty of this cake, besides how delicious it is, is that you only need one saucepan for the cake and one bowl for the frosting. If you don't have the sour milk called for in the recipe just use regular milk and add 1/2 tablespoon of lemon juice or vinegar.