To rehydrate the dried mushrooms, place in a bowl and cover with 200ml of boiling water. Leave to one side. After about 5 minutes, the mushrooms will have soaked up some of the liquid and be nice and rehydrated. Strain through a fine sieve, reserving the liquid, then roughly chop.
Place a pan over a medium heat and add 1 tablespoon of olive oil. Peel and finely slice to the garlic, pick the thyme leaves and add both to the pan when the oil is hot.
Once it begins to colour, tear in the fresh and rehydrated mushrooms along with the soaking liquid. Cook for 15 to 20 minutes, or until all cooked down with a beautiful rich flavour, stirring continuously.
Remove from the pan and briefly blitz in a food processor or roughly chop on a board. Leave to cool for 5 minutes, then transfer to a bowl.
Roughly chop the butter into cubes and add to the mushroom mix (it will start to melt a little with the heat).
Pick the parsley leaves and roughly chop, then stir through the mushrooms, with 1 teaspoon of truffle oil and a good pinch of sea sat and black pepper.
Peel and roughly chop the onion into wedges. Trim the celery and fennel, then chop the celery into 3cm chunks and cut the fennel into wedges. Add the veg to a large roasting tray along with the tomatoes and wine.
To prep the chicken, carefully place a rubber spatula under the skin – the easiest way to do this is from behind the neck. Gently push the spatula under the skin from the front, working your way across while moving towards to the back. Once you have created the space, carefully stuff (or pipe) the mushroom filling into it, massaging on the outside and pushing it in an even layer across the underside of the skin.
Place the chicken in the tray on top of the veg, drizzle over 1 tablespoon of olive oil and season generously. Roast for 1 hour 40 minutes, or until cooked through, but check after 1 hour 30 minutes. Cover with tin foil for the last 20 minutes if it is getting too much colour.
Once cooked, leave to rest for 10 minutes. Delicious served with seasonal steamed greens and boiled or roast potatoes.