Melt any remaining fat and juice from the roasted chicken tray in a flame casserole dish and melt on a medium heat. Tip in onion, carrot, parsnip, celery and garlic, and fry, partially covered, until soft on low heat for 8–10 minutes. Mix in plain flour, bay leaves and half thyme, cook for a few minutes, then add stock and chopped chicken. Bring back into a soft boil and cook for 15-20 minutes until everything is tender. Season.