In a large stock pot over medium heat, combine sausage, onions, and oil. Saute 4-5 minutes until sausage starts to brown.
Stir in garlic for 1 minute until fragrant.
Add chicken broth, tomatoes, beans, Italian seasoning, salt, and pepper and give it a good stir. Bring to a boil, reduce to a simmer, cover and cook for 10 minutes.
Stir in spinach for 2-3 minutes until wilted. Taste, add salt and pepper if needed, and garnish with grated parmesan cheese and black pepper if desired before serving.
