In a large dutch oven, saute italian sausage and onion until cooked through and not pink. Add in the garlic and cook for a minute more. Then add in tomatoes, chicken broth, basil, boullion cubes, and salt and pepper. Bring to a boil, then reduce heat and cover to simmer for about 15-20 minutes. Add tortellini and fresh, chopped spinach; simmer for about 10 minutes more or until tortellini is tender. Serve with crusty bread and salad for a dinner fit for company! ENJOY!