Preheat the oven to 400 F/ 200 C/ gas mark 6. Arrange the butternut squash pieces in a single layer on a large baking tray, season, drizzle with a little oil and bake for 35-40 minutes (or until tender and lightly browned). In the meantime make the chili.
In a large pot heat up the oil, add the bay leaf, allspice berries, garlic, onion and celery and fry over a medium heat for 3-4 minutes stirring often.
Add the beans (and water from 1 can) and using a potato masher mash them up a little (leave some beans whole). This will thicken the sauce.
Add the peppers, tomatoes, tomato paste, all the spices, stir, cover and bring to the boil, then simmer for about 20 minutes.
Remove from the heat, stir in the butternut squash (it should be ready by now) and cilantro. Adjust the seasoning as necessary and serve.
Roast the butternut squash separately and add into the chili after it's been cooked. (If you roast the squash as well as cook it in the chili it might get a little too soft and won't be as tasty).
Cook the chili while the butternut squash is in the oven.
I recommend partly mashing the beans for a thicker sauce (though this is optional).
Adjust the amount of chili powder to suit your taste. I used a moderate amount for a mild chili.
Serve with chopped avocado and lemon zest (highly recommended!), with rice, quinoa or taco/pita bread, or simply on its own.
Refrigerate leftovers for up to 3 days. This chilli tastes even better the next day!
Freeze individual portions in airtight containers for up to 3 months.