How to Make It
In a bowl, cover the beans with water and let soak overnight. Alternatively, in a saucepan, cover the beans with water and bring to a boil over moderate heat. Remove from the heat and let soak, covered, for 1 hour.
Drain and rinse the beans. In a large enameled cast-iron casserole, combine the beans and the prosciutto bone with 10 cups of water. Bring to a boil over moderately high heat, then reduce the heat to moderately low and simmer until the beans are tender but still intact, 1 1/2 to 2 hours.
Meanwhile, heat the olive oil in a large saucepan. Add the fennel, onions, celery, leeks and carrots and season with kosher salt and black pepper. Cook over moderate heat, stirring frequently, until the vegetables are softened, 15 to 20 minutes. Add the cabbage, bay leaf and 1 teaspoon crushed red pepper and cook, stirring, for 5 minutes.
Add the sautéed vegetables to the beans with the thyme and rosemary. If necessary, add more water to cover the vegetables. Bring to a boil over moderately high heat, then reduce the heat and simmer until the cabbage is tender, about 30 minutes. Season with salt, black pepper and crushed red pepper. Discard the prosciutto bone. Ladle the soup into bowls and serve with the Parmesan and Tuscan Kale Pesto.