Mix the ground chicken, grated parmesan, breadcrumbs, spinach, salt, pepper, garlic powder, onion powder, and dried Italian seasoning in a large bowl until combined.
Preheat the oven to 400 F. Pour the marinara in the bottom of an oven-safe skillet. Start to roll the meatballs and place them directly on top of the marinara. You should get about 15 meatballs.
Loosely tent with aluminum foil and bake for 30 minutes.
Once baked, uncover the foil and sprinkle the entire skillet evenly with shredded mozzarella. Place back into the oven and crank on the broiler. Broil until cheese is melted and bubbly, about 3 - 4 minutes.
Garnish with Italian parsley, shredded parmesan, and optional red pepper flakes. Serve with toasted baguette for dipping.