Skin the cooked chicken pieces and set them aside.
Heat the butter and oil in a large casserole dish.
Sauté the garlic, onions, and pancetta for 5 minutes until softened.
Add the mushrooms and thyme and sauté for another 5 minutes.
Pour in the wine and boil uncovered for 5 minutes to reduce by half.
Add the chicken stock and bring the mixture back to a boil.
Season with salt and pepper and add the chicken pieces to the sauce.
Simmer for 5 minutes to heat the chicken through, then remove chicken to a warm dish.
Boil the sauce until reduced by half, then stir in the cream and heat through.
Pour the sauce over the chicken and garnish with parsley to serve.