How to Make It
Preheat oven to 400°F.
Line a large rimmed baking sheet with foil; coat foil with cooking spray. Place chicken in a medium bowl. Add panko, 1/4 teaspoon salt, oregano, half of cheese, garlic, and egg; mix well to combine. Shape into 32 meatballs (about 2 tablespoons each) and arrange on prepared pan. Bake at 400°F for 15 minutes or until cooked through. Increase heat to high broil (do not remove pan from oven); broil 2 to 3 minutes or until lightly browned.
Meanwhile, heat oil in a large Dutch oven over medium heat. Add carrot, onion, and celery; cook 10 minutes or until softened, stirring occasionally. Stir in stock, pepper, bay leaves, and remaining 3/4 teaspoon salt. Bring to a boil; reduce heat, and simmer 15 minutes or until carrot is tender. Gradually add spinach, stirring just until spinach wilts. Gently stir in cooked meatballs. Sprinkle soup with remaining cheese.