Preheat the oven to 200oC/400oF. Set pot to boil on stove if using instant mashed potatoes.
Heat the oil in a large, deep frying pan. Add the onion, carrot and mushrooms and cook gently until softened – around 3–4 minutes. Add the chilli and cook for a further 2 minutes.
Add the beef, stirring well, until the meat is broken up and browned all over.
Stir in the flour, a little at a time, very thoroughly. Then add the hot stock and tomato purée and bring to the boil. Reduce the heat to a simmer.
Add the Worcestershire sauce and peas, season with salt and pepper, cover the pan, and cook for around 15 minutes. The juice should thicken up.
(Homemade mashed potato option). While you’re doing all this, cook the potatoes in a large pan of boiling salted water until soft, which will take around 20 minutes.
Drain, add the milk and butter and mash until smooth. Season to taste.
Spoon the meat mixture into a large ovenproof dish. Cover with mashed potato. Use a fork to make a corrugated pattern on top.
Cook in the oven until the top is golden brown – around 25 minutes.
