Heat oil in a Dutch oven over medium-high. Add sausage, cooking until browned. Remove sausage from pan; set aside.
Add more oil to pan if needed and add onion. Cook, scraping up browned bits on bottom of pan, and stir occasionally until onion is softened and translucent, 5 to 7 minutes.
Add garlic, rosemary, salt, and pepper. Cook, stirring constantly, 1 minute. Add beans, broth, and bay leaf.
Bring mixture to a boil over high. Add Parmesan rind if adding. Reduce heat to low; simmer, stirring occasionally, 15 minutes. Remove and discard bay leaf.
Ladle 2 cups mixture into a blender. Secure lid on blender, and remove center piece to allow steam to escape. Place a clean towel over opening. Process until completely smooth, 1 minute. Return pureed mixture along with sausage to remaining soup in pot and bring to a simmer over medium-high.
Add 1 cup dried pasta; simmer for 10 minutes. Remove Parmesan rind.
Add in kale; cook, stirring often, until wilted and slightly softened, 2 to 3 minutes.
Serve with Parmesan shavings if desired.