Heat the oven to 180.c fan
Place the turkey crown into a suitable sized roasting tray. Rub the butter evenly over the skin of the bird, sprinkle over half the thyme leaves and season well with sea salt and black pepper.
Set the turkey crown into the middle of the hot oven and roast for 1 hour 45 minutes basting the bird and turning it in the oven once or twice.
Take the tray out of the oven and lift the turkey onto a plate. Keep warm.
Pour the roasting juices out of the tray into a cup or measuring jug, then place the tray over a medium heat.
Spoon the fat off the top of the roasting juices and add it to the tray. When it is hot add the leeks, garlic and bacon lardons and cook, stirring regularly for 6 – 8 minutes.
Now add the mushrooms and chestnuts and cook for a further 10 minutes. Shake over the flour and using a wooden spoon work it into the vegetables.
Pour in the cider brandy and let it bubble away for a minute or so. Pour over the stock and the reserved roasting juices and bring to a gentle simmer.
Add the cream, stir well and cook the sauce for 5 - 6 minutes or until it’s nice and thick and rich.
Scatter over the chopped parsley and season the sauce well with salt and pepper.
Carve thick slices of turkey and divide between warm plates. Spoon over some sauce and bring the rest to the table.