- Preheat the oven to 200°C.
- Heat a large frying pan over medium heat. Add oil, onion, carrot and celery and fry for 5-7 minutes. Add mince and more oil if necessary and cook until the mince has browned, stirring often.
- In a small jug mix boiling water with half of the gravy sachet. Add rosemary, gravy and tomatoes to the mince and simmer for 10 minutes. Season with garlic salt then transfer to your oven-proof pie dish.
- To make the macaroni cheese topping: follow packet instructions.
- Spoon macaroni cheese over mince in the pie dish and sprinkle liberally with cheese.
- Bake in the oven for 35 minutes, until golden and the cheese has bubbled. Serve while hot. Yum!