Microwave for one minute on high. (The time may vary based on microwave and mug size. If you have an older microwave, it may take longer. After making the first one you will figure it out. You just don’t want to overcook the muffin, as it will dry out. As a test, I undercooked a muffin by 15 seconds and then popped it out of the mug to find it slightly uncooked in the center. I immediately returned it the mug, cooked for 15 seconds more, and the texture was fine. You may wish to try this method the first time.) The muffin will easily pop out of the mug with a gentle pry of a knife. It will be moist from the steam at first but will quickly dry as it cools. I like to cut the warm muffin in half and spread with a little butter.