1. Remove casing from sausage. Heat a 4-quart saucepan over medium-high heat. Add oil to pan; swirl to coat. Add sausage to pan, and cook until browned; stir to crumble. Add onion, celery, and carrot; sauté 4 minutes or until tender. Add garlic; sauté 30 seconds.
2. Stir in 7 cups water and next 6 ingredients (through bay leaves). Bring to a boil; stir in lentils. Return to a boil; reduce heat, and simmer, uncovered, 40 minutes or until lentils are tender.
3. Stir in spinach; cover and cook 2 minutes or just until spinach wilts. Remove and discard thyme sprigs and bay leaves. Ladle soup into bowls, and, if desired, sprinkle evenly with cheese.
MyRecipes is working with Let's Move!, the Partnership for a Healthier America, and USDA's MyPlate to give anyone looking for healthier options access to a trove of recipes that will help them create healthy, tasty plates. For more information about creating a healthy plate, visit www.choosemyplate.gov.