Chicken pot pie with cheddar pastry

Method

1. To make the pastry: mix the flour, mustard powder and salt in a bowl, then rub in the butter and lard until it resembles coarse crumbs, still with a few pea-size pieces of fat. Stir in the cheese, then make a well in the middle and slowly trickle in the egg, cutting the mixture together with a table knife. You may not need all the egg or you may need to add a little iced water – just enough to bring the mixture together into a soft dough. Wrap the pastry in cling film and chill for at least an hour – you can make it the day before.
2. Meanwhile, put the chicken pieces in a casserole with the carrot, celery, bouquet garni and salt. Pour in enough water just to cover, bring to a simmer and cook gently until the chicken is tender – about 20-25 minutes. Remove the chicken with tongs and set aside. Simmer the poaching broth hard to intensify the flavour until you have about 250ml stock left. When the chicken is cool enough to handle, strip the meat in large chunks. Discard the skin and bones.
3. To make the filling, melt the butter in a large-ish, heavy-bottomed pan over a medium heat. Add the lardons and cook until crisp. Lower the temperature and add the onion, carrot and celery, then cook gently, stirring now and then, for 5 minutes. Sprinkle with the flour and cook, stirring, for 2 minutes, then pour in the wine and reserved stock. Bring to a simmer, stirring, and cook until the sauce has thickened and is glossy. Remove from the heat, add the chicken, peas and pearl onions, then stir in the crème fraîche, parsley and, if you like, dill. Taste and season, then let it cool a bit.
4. Heat the oven to 180°C fan/gas 6. Roll out the pastry – I do this between 2 sheets of baking paper dusted with flour. Spoon the filling into a 1.9 litre baking dish, brush the edges with milk and drape over the pastry. Crimp to seal (or just press the pastry onto the edges), then make a few cuts in the top for the steam to escape. Brush with milk, then bake for 30-35 minutes until the filling bubbles through the cuts and the pastry is golden brown.