Place the Oreo cookies in a microwavable mug and use a fork to crush the Oreos into small crumbs. Alternatively, you can blitz the cookies in a food processor to create fine crumbs.
Pour milk in the cup and mix together until evenly distributed.
Place the mug in the microwave and cook on a high heat for 1 minute. If the mug cake is still runny, continue to cook in 10 second intervals until it has solidified.
Leave the mug cake to cool down for 1 minute, add your toppings and enjoy.