Preheat oven to 190°C/170°C fan/gas 5.

For the filling, heat the oliver oil in a frying pan and sauté the onion, carrots and mince for 5-6 minutes until golden. Add the stock, tomatoes, tomato purée, oregano and worcestershire sauce. Cook for 20-25 minutes until the liquid has reduced, then stir in the peas.

Boil the potatoes in lightly salted water for 20 minutes, or until tender, and drain.

Add the olive oil, milk and seasoning to the cooked potatoes, and mash until smooth.

Transfer the meat filling to an ovenproof dish. Top with the mashed potato and rough up with a fork. Place in the oven and bake for 45 minutes.