In a large mixing bowl, combine ground chicken, breadcrumbs, grated Parmesan, egg, two minced garlic cloves, Italian seasoning, salt, and pepper. Mix gently until combined. Shape into 1-inch meatballs.

Heat a skillet over medium heat and add olive oil. Once hot, add the meatballs in batches and brown for 5-7 minutes. Set aside after browning.

In the same skillet, add the diced onion, carrots, celery, and remaining minced garlic. Sauté for 5-7 minutes until softened and fragrant.

Pour in the diced tomatoes and chicken broth. Stir in white beans, fresh thyme, and bay leaf. Bring to a simmer.

Return meatballs to the skillet. Cover and transfer to a preheated oven at 375°F. Bake for 25-30 minutes.

Remove from oven, discard bay leaf and thyme. Ladle into bowls, garnish with parsley if desired, and serve hot.