Preheat the broiler. Line a sheet pan with foil and coat it with cooking spray.
Place the ground beef, pork, egg, parmesan cheese, breadcrumbs, Italian seasoning, 1/2 teaspoon of salt and 1/4 teaspoon of pepper in a bowl. Stir to combine.
Roll 1/2 inch sized meatballs out of the meat mixture and place on the sheet pan.
Broil for 8 minutes or until tops are browned.
While the meatballs are cooking, melt the butter in a large soup pot over medium heat.
Add the onion, carrot and celery to the pot and cook for 5-6 minutes or until just softened.
Add the garlic and cook for 30 seconds.
Pour in the chicken broth and acini de pepe, then season the soup with salt and pepper to taste.
Bring the soup to a simmer. Add the meatballs to the soup. Cook for 10 minutes or until pasta and vegetables are tender.
Stir in the spinach and cook for 2 minutes or until wilted.
Sprinkle with parsley, then serve.