Cooking the filling

1. Heat a large pan on a medium heat and add a good lug of olive oil.
2. Mix in onions, carrot, garlic, pepper and rosemary leaves.
3. Cook for 5 minutes, stirring occasionally, until the carrots have softened.
4. Mix in 2 tbsp of tomato puree and cook for a further 2 minutes.
5. Add the minced beef and brown for 10 minutes, though stirring occasionally
6. Pour in the Worcestershire sauce.
7. Mix in stock and let it simmer for 20 minutes.
8. Season with salt and pepper.

To make your mash topping

1. Clean the potatoes and boil these in a pot of salted water.
2. Boil until the potatoes are fork-tender.
3. Drain the potatoes in a colander and let it cool down slightly.
4. Remove the skin from the potatoes.
5. Mash the potatoes and add the butter. The warm of the potato would melt your butter.
6. Add milk, salt and pepper.
7. Mash until smooth and creamy.

To assemble

1. Preheat the oven to 180 degrees Celsius.
2. Pour the beef mixture to a large ovenproof baking dish.
3. Spoon the mash evenly over the top.
4. Top with cheese and bake for 20-25 minutes until golden.