Soak the beans overnight, or for a minimum of six hours.
Finely chop the onions, celery and garlic.
Strip the rosemary from the stems.
Wash and pat dry the carrots and cavolo nero.
Remove the top from the carrots and cut them lengthwise. Then slice each half into even, half moon slices of about 1 mm thickness.
Chop the leaves of the cavolo nero into thick strips and chop the stems finely.
Heat the oil in a pot, and add the bay leaves and peppercorns.
Over a medium heat, fry the onions, celery and garlic until soft and translucent without any colour.
Add the rosemary stripped from the stems.
Add the pre-soaked and drained cannellini beans, vegetable stock and season with salt. Cover and cook for 20 minutes or until the beans are soft and can be broken when pressed between your fingers. Once the beans are cooked, crush some of the beans with the back of a spoon to thicken the soup.
Add the carrots and cook for 10 minutes uncovered.
Finally, add the stems of cavolo nero followed by the leaves and cook for 5 minutes
Serve hot with cheese toast (optional)