Method

• 1.
  Begin this recipe 1 day ahead.
• 2.
  Place the chicken in a dish with the onion, celery, carrot, garlic and thyme. Pour in the wine, cover and refrigerate overnight. Remove the chicken and pat dry, strain the vegetables reserving the marinade and vegetables separately.
• 3.
  Preheat the oven to 180°C.
• 4.
  Heat half the oil in a large ovenproof casserole dish over medium-high heat. Add chicken, brown all over. Transfer to a plate and set aside. Add pancetta to casserole dish and fry 1-2 minutes, then add reserved vegetables, tomato paste and flour. Cook for 1 minute.
• 5.
  Add the reserved marinade and reduce by half, add the stock and return the chicken to the pan. Cover and place in oven for 2 hours. Set aside to cool slightly, then remove meat from bones, and shred.
• 6.
  Heat remaining oil in a frypan. Add mushrooms and fry over medium heat for 2-3 minutes. Place the shredded chicken, vegetables and mushrooms in a bowl. Add enough of the cooking liquid to moisten but not swamp the dish. Divide between individual ovenproof serving dishes, cover evenly with the mashed potato and return to the oven for a further 20 minutes or until golden brown. Serve immediately.