Peel the apple and cut it into thin slices. I find that thinner slices cook evenly in the microwave. Place slices in a microwaveable mug or small bowl. Microwave for 60 seconds.
Meanwhile, combined the remaining ingredients and crumble together with a fork.
Stir the cooked apples and then sprinkle the topping on top. Microwave for 30 seconds. Stir and then microwave for an additional 30 seconds.
Allow to cool for 5-10 minutes and then top with a of ice cream or a dollop of whip cream.
Recipe by Life at Cloverhill at https://lifeatcloverhill.com/2013/10/apple-crisp-mug.html