1. Heat the oven to 180C/Gas Mark 4.
2. Put the peeled and quartered potatoes in a pan of salted water and bring to the boil. Simmer until tender.
3. Meanwhile, heat the oil in a large frying pan over a medium heat and fry the onion and carrot with a sprinkling of salt until tender then remove from the pan and put to one side.
4. Increase the heat and fry the mince, making sure you get plenty of golden brown bits. Don’t worry, as long as you keep it moving you won’t burn it.
5. Return the onion and carrots to the pan and add the water. Use a spatula to get all the crispy meat juices off the bottom of the pan as the water heats up. This will only add flavour.
6. Once the water is simmering, add the tomato puree, the crumbled stock cube, the Worcestershire sauce and the peas. Bring to the boil again and leave to simmer for 15-20 minutes and add any further seasoning if required. Pour in some more water if it starts to look a bit dry.
7. Once the potatoes are cooked, drain and mash together with the butter, milk and some salt and pepper.
8. Put the cooked mince mix in the bottom of a baking dish and spread the mashed potato on top, fluff it up a little with a fork so you get crispy bits on top as it cooks. Bake for 25-30 minutes or until golden brown.