Mix ground beef, breadcrumbs, egg, garlic, Parmesan, Italian seasoning, salt, and pepper.
Roll into 1-inch meatballs (about 24 total).
Heat olive oil in large pot over medium heat.
Add onion, carrots, and celery. Cook 5 minutes.
Add garlic. Cook 30 seconds.
Add broth and tomatoes. Bring to boil.
Drop meatballs in one at a time.
Reduce to simmer. Cook 15 minutes.
Add pasta. Cook 8 to 10 minutes.
Stir in spinach. Cook 2 minutes until wilted.
Season with salt and pepper.
Serve with parsley and Parmesan.