Heat a large pot over medium heat and add the chicken breasts or thighs. Sauté until browned, about 5-7 minutes.
Add chopped carrots, celery, onion, and garlic to the pot. Stir and cook for another 5 minutes.
Season with Italian seasoning, salt, and black pepper. Pour in the chicken broth and bring to a boil.
Once boiling, reduce the heat to a simmer and add the potato gnocchi. Cook for about 5 minutes or until the gnocchi are tender.
Stir in the chopped spinach and half-and-half or heavy cream. If using cornstarch for thickening, mix it with cold water and add to the pot. Simmer for an additional 3-5 minutes.
Serve hot, garnished with fresh parsley or grated Parmesan cheese if desired.
