In a large bowl, combine the ground chicken, Italian seasoned breadcrumbs, beaten egg, minced garlic, salt, pepper, and ¼ cup of grated Parmesan cheese. Mix gently with your hands until just combined. Do not overmix.

Roll the chicken mixture into small meatballs, about 1 inch in diameter. You should have approximately 24-30 meatballs.

Pour the chicken broth into a large pot and bring it to a boil over medium-high heat.

Carefully add the chicken meatballs to the boiling broth. Reduce the heat to medium-low, cover the pot, and simmer for 15-20 minutes, or until the meatballs are cooked through.

Stir in the acini di pepe pasta and cook according to package directions until al dente.

Add the baby spinach to the pot and stir until it wilts, about 3-5 minutes.

Ladle the soup into bowls and top with additional grated Parmesan cheese before serving.