Mug cakes first became popular a few years ago. The concept is simple: you mix a few ingredients in a mug or a cup and microwave it to make an instant treat. These little cakes are tender and moist, with a texture that is simply divine. Chocolate peanut butter cake in a cup is so delicious and so simple to make; it takes just five minutes This cake is moist and rich and has the most wonderful fudgy peanut butter flavor. Keep the ingredients for this recipe on hand so you can make it anytime you'd like. Teach your kids how to make this recipe too (and about microwave safety) and they can have a snack when they get home from school or if they are just hungry.