In a large stockpot, or a Dutch oven, over medium heat, brown Italian sausage with onion, bell pepper and garlic.  Cook until sausage is brown and vegetables have softened.  Break sausage up into small pieces.  Add broth, beans, tomatoes, Parmesan cheese rind (if using), bay leaf, red pepper flakes, and Italian seasoning.  Bring to a boil.  Cover and reduce heat to a simmer.  Cook for about 20 minutes, stirring occasionally.

Remove bay leaf.  Add collard greens or kale.  Increase heat and bring soup to a boil.  Reduce heat and return to a simmer and cover.  Cook for another 10 minutes or until collards are tender.  Remove from heat and stir in basil.  Top with grated Parmesan cheese.