Add wet ingredients in the order listed: milk, oil, peanut butter, egg, vanilla. Mix until just moistened. Do not over mix.
Sprinkle chocolate chips and give one good stir. I used a small palm-ful of chips.
Cook in microwave for 1 minute on high. Depending on the wattage of your microwave it my take a bit longer to cook. I used a 1200 watt microwave and my cake was done after 1 minute. If your cake is not done after 1 minute, continue to cook in 30 second intervals until cooked through.
This might not be a typical cake consistency for you as it is spongy more than moist. Believe me though, this is oh so delicious and definitely worth a try. Enjoy!
Notes
You can easily make a different type of cake with this recipe. Just switch a few ingredients depending on what you are in the mood for and have a delicious cake in minutes!