Start by cutting the chicken in two lengthways; you can ask your butcher to do this for you, but it’s very easy to do yourself. Take a pair of kitchen scissors or shears and cut along one side of the spine as if you were spatchcocking the chicken. Then do the same down the breast. Season generously all over and leave for about an hour for the salt to penetrate.

After the hour, get a large heavy-based pot that ideally fits both halves of the chicken, drizzle in a splash of oil and crank up the heat. When the oil is shimmering, fry the two pieces of chicken on both sides until golden brown all over.

When the chicken is browned, roughly chop the veg and chuck in with the bay leaves. Top up with water so that the chicken is just covered. Season generously with salt and bring up to the gentlest of simmers with the lid on for 30 minutes, until the chicken is just cooked through.

When ready, remove the chicken from the pot and leave to cool. When cool enough to handle, strip the chicken meat from the carcass and place it in a bowl.

Halve the sticks of celery lengthways and slice, then chop the leeks into 2cm rounds. Remove any rind from the bacon before cutting into chunks, then place in a large pan with the butter and fry to render out the fat.

Add the celery and leeks along with a ladle of the chicken stock, then put the lid on and slowly cook until completely tender.

At this point, strain the chicken stock and measure out 600ml. Taste the stock and season with salt as necessary.

Add the flour to the leeks and mix well, cooking for a few minutes, until the flour smells a little biscuity, then pour in the wine and mix again.

Now add the chicken stock a ladle at a time, stirring until it is completely mixed in before adding the next ladle.

When all the chicken stock has been added, turn off the heat and pour in the cream. Add the chicken meat, mustard and finely chopped tarragon. Mix thoroughly and taste – adjust the seasoning until it’s perfect.

Preheat your oven to 200°C fan. Whisk an egg and brush the rim of your dish. Place the rolled-out pastry on top and crimp the edges.

Brush the top with more egg wash, then sprinkle with fennel seeds and season with salt and pepper. Pierce a hole in the middle for the steam to escape, then place in the oven for about 30 minutes, until the top is golden brown and puffed.