Start by preheating your oven to 400°F.
In a large bowl, combine the ground chicken, egg, panko, half of the parmesan, minced garlic, onion powder, oregano, salt, pepper, and crushed red pepper flakes.
Mix until everything is just combined. Overmixing will make the meatballs tough, so stop as soon as it's evenly incorporated.
Pour the marinara sauce into your baking dish. Using a cookie scoop, portion the chicken mixture into 12 to 16 meatballs and place them directly on top of the sauce, spacing them evenly.
Top the meatballs with the remaining mozzarella and parmesan. Transfer the dish to the oven and bake for 25 to 28 minutes, or until the chicken reaches an internal temperature of 165°F and the cheese is melted and starting to brown in spots.
Pull the dish out, scatter fresh basil on top, and serve over pasta or on its own with bread for dipping.