Fry the peppers and onions in the butter and oil until soft and translucent, about 10 mins. Move the peppers and onions to the side then add the chicken. Fry until cooked through and a bit coloured. Add spices and salt. Fry briefly then add the hot sauce, cream and parmesan. Lay the sliced mozzarella on top. Cover and cook on low for 5 minutes. Remove lid, take off heat and dump into subs.