In a large pot or Dutch oven, brown the sausage over medium heat, breaking it up with a spoon. Drain off any excess grease.

Add the olive oil, onion, and garlic to the pot. Cook until the onion is softened, about 5 minutes.

Pour in the chicken broth and bring to a boil. Add the cannellini beans, kale, oregano, and red pepper flakes (if using). Season with salt and pepper to taste.

Reduce the heat and simmer for 20-30 minutes, allowing the flavors to meld.

Serve hot, garnished with grated Parmesan cheese.