Method

• Preheat the oven to 200C/180Cfan/Gas6.
• Grease a large lidded hob proof/ovenproof casserole dish with olive oil.
• In the cavity of the chicken place the lemon, onion, carrot, celery and 3 sprigs of fresh thyme. Season the chicken generously with salt and freshly ground black pepper. 
• Brown the chicken on all sides in the casserole dish and remove.
• Add the white garlic, Black Garlic cloves and remaining 3 sprigs of thyme, white wine and chicken stock to the base of the casserole dish. Place the chicken back on top of the garlic.
• Bring the liquid to a simmer, cover the casserole dish with the lid. Put in the oven for 1 hour.
• After 1 hour, take off the lid and roast the chicken uncovered for a further 15 minutes. Check to see if the chicken is cooked by piercing the chicken thigh with a knife; the juices should run clear if cooked. If not, return the chicken to the oven uncovered for an extra 10 minutes.
• Lift the chicken onto a carving dish. Cover with foil and leave to rest for 10 minutes.
• While the chicken is resting, remove the black and white garlic cloves from the sauce. Squeeze the white garlic cloves from their skins. Set aside with the black garlic cloves. Mash the black and white garlic together with a fork.
• Remove the herb sprigs from the sauce. Return the casserole dish to the hob, bring the sauce to a simmer then reduce by a third. Put the mashed black and white garlic back into the sauce. Taste and adjust the seasoning.

To Serve: carve the chicken and serve with the garlic sauce.