Preheat the oven to 190C/375F/Gas 5.

Heat the oil in a large pan. Add the onion, carrot and celery and cook over a medium heat for five minutes until soft.

Add the minced beef and cook for three minutes or until brown.

Add the beef stock, tomatoes, purée, ketchup, Worcestershire sauce, bay leaf and thyme.

Cover and simmer for 30 minutes. Season.

Meanwhile, to make the topping, boil the potatoes and parsnips in water until soft. Drain and mash with the butter and milk.

Spoon the meat mix into an ovenproof dish. Top with the mash and then cheese and bake for 30 minutes until golden brown.