Heat the olive oil in a Dutch oven over medium heat.
Add onion, carrot and celery and sauté until softened, 5-6 minutes, stirring occasionally.
Add the chicken broth and sherry and bring to a boil.
Add the pasta to a simmering broth and cook for 5-6 minutes, until pasta is tender.
Add meatballs to soup and cook for another 2-3 minutes.
Stir in spinach and cook for another 2 minutes, until the spinach is just wilted.
Ladle into soup bowls and sprinkle each with extra Parmesan cheese.
Serve hot.