In a medium-sized mixing bowl, add ground chicken, ground chicken sausage, breadcrumbs, egg, Italian seasoning, and salt and pepper. Stir until combined. Roll into one-inch meatballs, making about 25-30.
In a large pot, add olive oil, diced yellow onion, diced carrots, diced celery, and minced garlic. Cook for 2-3 minutes, or until tender.
Add chicken stock, uncooked acini di pepe pasta, and the shaped meatballs to the pot. Bring the soup to a boil, then reduce the heat to a simmer. Cook for about 10 minutes, or until the meatballs are cooked through and the pasta is tender.
Stir in chopped spinach and allow to wilt. Season with salt and pepper, then top with grated Parmesan cheese.
