In a large stockpot, heat oil over medium-high, add the onion and sauté until translucent, about 5 minutes. Add garlic cook for 1 minute or until fragrant. Add sausage, salt, and pepper; cook until sausage is no longer pink. Stir in crushed tomatoes and chicken broth; bring to a boil, reduce heat to low. Cover and simmer 10-15 minutes. Add ravioli and cook according to package directions or until tender. Stir in spinach and basil. Serve with grated Parmesan.