Roast chicken, ham and leek pie

Method

1. Heat the oven to 200°C/180°C fan/gas 6. Remove any giblets from the cavity of the chicken (freeze for making stock), then stuff it with the thyme, lemon and bay leaves. Tie the legs together with string, if you like (not essential), pat dry with kitchen paper, then rub all over with 20g of the butter. Season well. Scatter the onion in the centre of a lightly oiled roasting tin, then put the chicken on top. Cover with foil and roast for 1 hour 20 minutes. Uncover and roast for a further 30 minutes or until cooked through and golden.
2. Meanwhile, for the pastry, put the 250g butter in the freezer for 1 hour. Sift the flour and salt into a large bowl, remove the butter from the freezer, coat in flour, then coarsely grate into the bowl, dipping it into the flour now and then. Mix the butter into the flour, then stir in the water to make a soft, pliable dough. Bring together into a ball, knead briefly on a lightly floured surface, wrap in cling film and chill until needed.
3. Cook the leeks in a frying pan or saucepan with the remaining 15g softened butter for 3-4 minutes. Cool.
4. Lift the cooked chicken onto a board and, when cool enough to handle, remove the meat in small chunks, putting the skin, bones and herbs from the cavity into a large pan. Discard the lemon. Add the stock to the pan and simmer for 30 minutes. Strain; skim any excess fat from the surface. Mix the cooked chicken in a bowl with the cooked ham, leeks, peas and parsley.
5. Discard the excess oil from the roasting tin, put the tin directly over a medium heat and fry the onion a little longer if not well browned. Whisk in the flour, then gradually add the stock, scraping the base of the tin with a wooden spoon to release all the colour and flavour. Simmer until reduced to 600ml, stir in the cream and season to taste. Strain onto the chicken mixture, mix together well, cover and chill.
6. Put a baking tray onto the middle shelf of the oven and heat to 190°C/ 170°C fan/gas Cut off two thirds (about 500g) of the pastry and roll out on a lightly floured surface into a disc about 30cm in size. Use to line the base and sides of a buttered shallow 23cm loose-bottomed cake tin, leaving 1cm overhanging. Spoon in the chicken mixture, pressing it in well, and level the top.
7. Beat the egg yolk with 1 tsp cold water and brush the overhanging pastry with it. Roll out the rest of the pastry into a smaller disc measuring about 24cm, lay it over the top of the pie and press the edges together to seal. Brush the edge with yolk again, fold back on itself to make a better seal, then crimp. Brush the pie with more egg yolk and make a small hole in the centre of the lid.
8. Bake for 50-60 minutes, covering loosely with foil if it browns too quickly. Carefully remove from the tin and serve cut into wedges.