Shepherd's pie

1. Heat the oil in a medium saucepan, then add the onion and carrots for a few minutes. When they are soft, turn up the heat, crumble in the beef and brown.
2. Add the tomato purée and Worcestershire sauce, then fry for a few minutes. Pour over the stock, bring to a simmer, then cover and cook for 40 minutes, uncovering halfway.
3. Meanwhile, heat the oven to 180°C (fan 160°C) then make the mash. Boil the potatoes in salted water for 10-15 minutes until tender. Drain, then mash with the butter and milk.
4. Put the mince into an ovenproof dish, top with the mash and ruffle with a fork. 
5. The pie can now be chilled and frozen for up to a month.
6. Otherwise bake for 20-25 minutes until the top is starting to colour and the mince is bubbling through at the edges.

Baking from frozen

To bake from frozen, cook at 160°C (fan 140°C) for 1 hour to 1 hour 20 minutes until piping hot in the centre. Flash under the grill to brown, if you like. Leave to stand for 5 minutes before serving.