Select an 8x8x2″ square pan or a 9″ round cake pan. Place all ingredients except the vinegar in the pan. Stir with a fork or wire whisk until thoroughly blended.
Add the vinegar and stir quickly to thoroughly blend, and immediately place in the hot oven. There must be no delay in baking after the vinegar is added.
Bake for 20 to 25 minutes or until the center is slightly puffed and the sides begin to pull away from the pan. Cool on a wire rack.
Sprinkle the top with confectioner’s sugar or frost with chocolate frosting.
Recipe Notes
Cooking ahead: Six-minute chocolate cake is better if allowed to mellow for a day.