To a large mug, add all the ingredients and mix together with a small whisk, fork, or spoon.
Pop in the microwave to cook for about 90 seconds to 2 minutes, until a toothpick comes out clean in the center. You don't want to overcook it or it will be very dry.
Add toasted marshmallows on top and/or hot fudge sauce.
Allow it to cool for one to two minutes and then enjoy.