Rub 300 g plain flour with 150 g cold cubed unsalted butter until it resembles coarse breadcrumbs. Stir in 1 egg yolk and bring it together with 3–4 tbsp of cold water until it forms a dough.

Lay your chicken legs on a tray, season with salt and pepper and roast at 200°C for around 35–40 minutes. Save the juices from the tray.

Strip the meat while still warm and roughly tear into bite-sized chunks, discarding bones.

While the chicken cooks, fry diced bacon in a little oil until just crisp, then add sliced onions and leeks and soften gently. Add sliced mushrooms and cook off their moisture, then stir in minced garlic.

Scatter in a spoonful or two of flour and stir to make a roux around the vegetables. Splash in white wine and stir until thickened and smooth, then loosen gradually with a little chicken stock and roasting juices.

Stir through both wholegrain and Dijon mustard to taste, then add the shredded chicken and chopped flat-leaf parsley. Taste for seasoning and let the filling cool completely.

Roll out 2/3rds of the pastry and line your pie dish, letting it overhang slightly. Pile in the cold filling, then roll out the second disc and lay it over the top.

Trim and crimp the edges together, cut a small steam hole, and brush all over with beaten egg.

Bake at 180°C until deep golden and crisp (around 35–40 minutes). Let it rest for 10 minutes before slicing so the filling settles.