Halve the squashes and scoop out the seeds and pulp. Roast for 30-45 minutes until tender.
Meanwhile prepare the chilli. Heat the oil in a large heavy pan over a medium high heat. Add the onion and celery, reduce heat to medium and cook for about 10 minutes, stirring occasionally, until soft.
Add the peppers and cook for a further 10 minutes, stirring frequently, then stir in the garlic and cook for another minute.
Stir in the chilli, cumin and herbs. Season with salt and pepper. Stir again then tip in the tomatoes. Simmer, uncovered, for 30 minutes, then add the beans and cook for 10 mins more.
Remove the bay leaves , stir in the lime juice and coriander and check seasoning. Fill each roasted squash half with the chilli mixture and top with crumbled cheese and or/ sour cream .