Soak beans overnight and then rinse. Heat a large soup pot over medium heat and add 1 tablespoon olive oil. Add onion, carrot, celery, and garlic, saute for 2 minutes. Add beans, bay leaf, rosemary and enough water to cover the beans by 2 inches. Bring to a boil and then cover and simmer for 1 hour. Add Parmesan rind if using and cook until tender, about another 30 minutes. Once soft, use immersion blender to puree part of the soup or put 1/3 of soup into a food processor and then pour back in. Add salt and pepper to taste. Serve with a drizzle of olive oil if desired.