Heat the oil in a large flameproof casserole dish.
Add the onion, celery and peppers, and fry for 5 mins.
Add the garlic and paprika, and cook for a further 3 mins.
Stir in the tomatoes, stock and butter beans, and season well. Bring to the boil, then nestle the chicken thighs into the sauce. Cover with a tight-fitting lid and put in the oven for 45 mins.