Crispy topped Cumberland pie

2 celery sticks, sliced
1 onion, chopped
2 large carrots halved lengthways, then chunkily sliced
5 bay leaves
3 thyme sprigs
2 tbsp vegetable oil
1 tbsp butter
2 tbsp each plain flour, tomato purée and Worcestershire sauce
2 beef stock cubes crumbed or stock pots
600ml hot water
850g braising beef cut in large chunks
850g large potatoes
25g each mature cheddar and Parmesan finely grated

1. Heat oven to 160C / 140C fan / gas 3. Soften celery, onion, carrots, bay and 1 sprig thyme in a casserole with 1 tbsp oil and butter for 10 mins. Stir in flour, followed by purée, Worcestershire sauce and stock cubes / pots.
2. Gradually stir in 600ml hot water, then tip in beef and bring to a gentle summer. Cover and cook in the oven for 2hrs 30 min, then uncover and cook for 30 min uncovered or until sauce is thick and meat is tender.
3. Cook potatoes in a pan of salted boiling water until 3/4 done.
4. Depending on size or depth of casserole trf to baking dish or leave on shallow casserole. Slice potatoes into 1cm rounds and toss with seasoning, oil and cheese and thyme. Layer on beef and scatter cheese as you layer. If you like you can freeze this dish as is for 3 mths. If not increase oven to 200C / 180C fan / gas 6 and bake until golden ad crispy and sauce bubbling. Serve with peas...