Add the oil to a large, hot pan and fry the bacon until brown (not burnt!) and the fat has rendered down.

Remove the bacon out of the pan, leaving a little fat and add a knob of butter. When melted, add the leeks and sweat on a low heat for 5-10 minutes until they are soft and collapsed.

Add the mushrooms and turn up the heat to get all the water out of the mushrooms and stir occasionally so that the leeks can’t stick. When the water has evaporated after 5 or 6 minutes, brown slightly, then add the bacon back to the pan.

Add the flour, stir, and cookout for a few minutes. Add the stock and stir to make a lovely gravy. Add the thyme, chicken (any other leftovers bits from the roast like pigs in blankets or stuffing!) and simmer for 10-15 minutes until thick and heated through.

Place a sieve over a medium pan and place the chicken mixture into the sieve, so as to extract the gravy into the pan. Lightly press your chicken mixture to get most of the gravy out, so that it isn’t too wet and make the pastry soggy.

Move the chicken mixture to your pie dish. Leave to cool slightly or completely if you are preparing ahead of time.

Take the pastry out of the fridge and lay it out. Cut a few strips of 1cm thick pieces of pastry off the edges of the pastry sheet (if using shortcrust). Wet the edge of the pie dish with water and stick the strands to the dish as a base to set the lid on. Press gently to fix.

Brush these bits of pastry on the dish with water and place the whole piece of pastry on top. Press down gently. Use a knife to cut off the excess pastry and if you want, save the extra bits to make jam tarts!!

Crimp the edge of the pie with the end of the knife. Brush with beaten egg, and poke 2 holes in the top to let the stream out.

Place in a preheated oven (180 degrees) for about 25 minutes (35 if the mixture was cold), being careful that the top doesn’t brown too quickly. It will sit quite happily for 10 minutes on the work surface when cooked.

Reheat the gravy, dish up the pie with seasonal greens and enjoy!