Creamy Tortellini Soup

1 lb. Sweet Italian sausage

1 yellow onion, diced

2 large carrots, peeled and diced

2 stalks of celery, diced

4 garlic cloves, minced

¼ c. all-purpose flour

1 (14.5 oz.) can diced tomatoes

5 c. chicken broth

14 oz. refrigerated cheese tortellini*

Kosher salt and cracked black pepper, to taste

2 cups baby spinach, chopped

2 cups heavy cream

Shredded Parmesan cheese, for topping