Place beans in a large bowl. Add enough cold water to cover and let stand overnight. Drain and rinse beans thoroughly.
Prepare Meat Broth. Place beans in a large saucepan. Add water, broth, potato, carrot, celery and prosciutto rind or salt pork. Cover and bring to a boil. Reduce heat. Simmer 50 to 60 minutes, stirring occasionally.
Press tomatoes through a food mill or sieve to remove seeds. Heat oil in a medium saucepan. Add parsley, garlic and onion. Sauté over medium heat 2 to 3 minutes. Add pancetta. Sauté until pancetta is lightly browned. Stir in tomato pulp and season with salt and pepper. Reduce heat. Cook uncovered 15 to 20 minutes.
With a slotted spoon, place potato, carrot, celery and half the beans in a blender or food processor. Process until smooth. Return to saucepan. Add tomato mixture. Simmer uncovered 10 minutes. Taste and adjust for seasoning.
Toast bread until golden on both sides. Place 1 slice toasted bread in each soup bowl. Sprinkle generously with Parmesan cheese. Ladle soup into bowls.