Heat olive oil over medium heat in a large soup pot or Dutch oven. Add onion and bell pepper and sauté for about 7 minutes. Stir in garlic and cook for 1 minute, stirring often.
Pour in chicken broth and water. Bring to a boil. Stir in quinoa, and cook, partially covered, for 15 minutes over medium heat.
Stir in chicken sausage and baby spinach, and cook for 10 minutes. Serve with grated parmesan cheese if desired.