Gather the ingredients. Add milk, flour, and baking powder in a 12-ounce microwave -safe mug. Straightforward mug cake that you make from the microwave! A peanut butter mug cake stuffed with warm Nutella is a fast dessert certain to fulfill your cravings. In minutes you have a single dessert with a gooey caramel centre. May Nutella cake in mug is an individual cake which can be prepared in minutes