Creamy Chicken-Mushroom Casserole

RECIPE:
1 tblsp olive oil, 1 of butter
2 chicken breasts cut into pieces, dredged in seasoned flour.
salt and black pepper
1 onion,1 carrot, 1 stick celery finely chopped
2 cups chopped field mushrooms
small bunch chopped of parsley
1/2 teaspoon dried thyme
1 heaped tablespoon plain flour
1 and 1/2 cups chicken stock
1/2 cup cream
Heat the oil and butter in a frying pan until sizzling. Add the chicken to the pan and cook for 2–3 minutes on each side until sealed.  Remove and put aside.  Add onions, carrots and celery and fry over moderate heat for 3–4 minutes, or until softened.  Add flour and stir through.  Slowly add chicken stock while stirring to form sauce.  Add mushrooms to the pan with thyme, salt and pepper.  Put lid on.  Cook for 10 mins at LOW heat. Test if vegetables cooked, add chicken and cook further 5 mins or until chicken cooked through (don't boil or you'll overcook chicken and curdle cream.  Needs to be low heat).  Add parsley and cream and stir through.  Can keep in warm oven until ready to serve.  Serve over jasmine rice or cooked potatoes.