Reserve half the mozzarella. Place remaining mozzarella in a 350ml capacity microwave safe mug with remaining ingredients and mix until well combined. Top with reserved mozzarella.
Microwave on high (100%) for 1 1/2 - 2 minutes, until muffin is just firm in the centre and starts to come away from the side of the mug. Serve warm.
TO REFRIGERATE:
Store my cooked mug muffins, covered in their mugs (without any toppings), for up to 3 days. Reheat in microwave and add toppings.
TO FREEZE:
Store my cooked mug muffins as above for up to 2 months. Thaw overnight in fridge and serve cold or reheat in the microwave until hot, adding toppings to serve.