In a large mixing bowl, combine ground chicken, breadcrumbs, parmesan cheese, beaten egg, minced garlic, finely chopped onion, salt, and pepper. Mix gently until just combined and form into 1-inch meatballs.

In a large pot, heat olive oil over medium heat. Add meatballs in batches, sear for about 4-5 minutes until browned on all sides. Remove and set aside.

In the same pot, add more olive oil if needed and sauté diced onion, carrots, and celery for 5-7 minutes until they soften.

Pour in chicken broth and water, scraping the pot to release browned bits. Bring to a gentle simmer.

Add small pasta and simmer for about 8-10 minutes or until al dente. Stir occasionally.

Return meatballs to the pot with accumulated juices. Stir in spinach and cook for an additional 2-3 minutes until wilted.

Taste and adjust seasoning with more salt and pepper if needed. Serve warm with crusty bread.