If the batter is still not set after 1 minute, do a blast of 10 seconds increment. This recipe is for 1 only. To increase serving, you can either multiple ingredients, prepare it in a bowl then divide the batter to individual mugs and cook indivdually, or mix batter in each mug individually. Do not heat all the cups in the microwave at once or it will be unevenly cooked.
Adapted from 5 Minutes Mug Cake by Jennifer Lee