Heat 1 tbsp of the oil in a wide casserole or big frying pan and fry the chicken for a few mins to brown. Tip out onto a plate. Add the onion to the pan with 1 tbsp more oil and fry for 5 mins until almost softened. Add the celery and fry for another 2 mins, then tip out to join the chicken. Add the remaining oil, bay leaves and flour to the pan and cook into a paste. Carry on cooking, stirring constantly (with a splash of water if you need), until golden brown, then stir in the spices for 2 mins.
Gradually stir in the stock until smooth and saucy. Return the chicken and veg to the pan, along with the peppers, cover and simmer gently for 15 mins. Stir in the ham, cover and simmer gently for 10 mins more. Check for seasoning, then serve, sprinkled with the spring onions mixed with the chopped parsley.