How to Make It
Preheat oven to 300°F with rack in middle.
Bring 6 cups water to a boil in a Dutch oven or wide heavy pot with tightly fitted lid.
Add beans, Parmesan rind, rosemary, garlic, ½ teaspoon of the salt, and the salt pork, if using, to pot. Reduce to a simmer; cover and cook 30 minutes.
Transfer pot to oven. Bake, covered, until beans are tender, about 1½ hours, adding water as needed to keep beans covered (check every 30 minutes).
Remove pot from oven; remove and discard garlic cloves, rosemary, and Parmesan rind. Stir in pepper and remaining 1 teaspoon salt. Serve warm, garnished with fresh rosemary sprigs, if desired.