No-fuss shepherd's pie

Ingredients

• 1 tbsp sunflower oil
  
• 1 large onion
  
  , chopped
• 2-3 medium carrots
  
  , chopped
• 500g pack lamb mince
• 2 tbsp tomato purée
• large splash Worcestershire sauce
• 500ml beef stock
• 900g potato
  
  , cut into chunks
• 85g butter
  
• 3 tbsp milk
  

1. Heat the oil in a medium saucepan, then soften the onion and carrots for a few mins. When soft, turn up the heat, crumble in the lamb and brown, tipping off any excess fat. Add the tomato purée and Worcestershire sauce, then fry for a few mins. Pour over the stock, bring to a simmer, then cover and cook for 40 mins, uncovering halfway.
2. Meanwhile, heat the oven to 180C/ fan 160C/ gas 4, then make the mash. Boil the potatoes in salted water for 10-15 mins until tender. Drain, then mash with the butter and milk.
3. Put the mince into an ovenproof dish, top with the mash and ruffle with a fork. The pie can now be chilled and frozen for up to a month. Bake for 20-25 mins until the top is starting to colour and the mince is bubbling through at the edges. (To bake from frozen, cook at 160C/fan 140C/gas 3 for 1 hr-1 hr 20 mins until piping hot in the centre. Flash under the grill to brown, if you like.) Leave to stand for 5 mins before serving.