For the mince blend:
For the mashed potato:
Preheat oven to 180c.
Sauté the onion and carrot in a little olive oil for a few minutes. Add the lamb and mushrooms, cooking on a medium high heat for 10 minutes. Season well and stir occasionally.
Add the tomato purée and Worcestershire sauce. Cook for 1 more minute, then add the stock. Bring to the boil then reduce to a simmer, cook for a further 10 minutes.
Meanwhile, boil the potatoes until soft, drain and leave to cool a little. Mash with the butter.
Tip the meat and mushroom mince into an oven dish and top with the mash potato. Make ridges all over with the tines of a fork. Dot a little butter and black pepper over the mash.
Cook for 20-25 minutes until golden brown and bubbling. Serve with steamed lemon broccoli or other seasonal greens.