In a large mixing bowl, combine the ground chicken, chopped spinach, grated Parmesan cheese, breadcrumbs, softened cream cheese, egg, minced garlic, Italian seasoning, salt, and pepper. Mix until just combined, being careful not to overwork the mixture.
Form the mixture into evenly sized meatballs, about 1 to 1.5 inches in diameter.
Heat the olive oil in a large skillet over medium heat. Add the meatballs in batches, browning each side for 3-4 minutes until golden.
Reduce heat to low and pour marinara sauce over the meatballs. Cover and simmer gently for 10-12 minutes until cooked through.
Serve the meatballs hot with extra sauce. Enjoy with pasta, crusty bread, or cauliflower rice.