In a large stockpot or Dutch oven set over medium heat, add the oil. When the oil is hot, add the sausage and cook until browned, about 5 minutes; drain any excess fat.
Stir in the garlic and onion; cook until fragrant. Sprinkle in the oregano, basil, red pepper flakes, paprika, salt, and black pepper. Add the bay leaf and then pour in the chicken broth. Bring to a boil, then add the potatoes and lentils and cook for 10 minutes.
After the 10 minutes, add in the tomatoes and zucchini, and continue simmering for 15 minutes or until the lentils are tender. Stir in the spinach and let it wilt, about 2 minutes. Serve immediately, topped with Parmesan shavings if desired.
Notes
-I used a combination of sweet and hot Italian sausage so that our toddler could enjoy it too. Feel free to use any combination you prefer.STORE this Tuscan Lentil Soup in an airtight container in the refrigerator, where it will stay good for up to 5 days. To FREEZE, pour into freezer-safe containers, leaving some space for expansion, and it will last for up to 3 months.To REHEAT, thaw overnight in the fridge if frozen, then warm on the stove over medium heat until hot. Alternatively, microwave in a suitable container, stirring occasionally, until heated through.