Heat the oven to 400°F. Place a 12-well muffin pan on the baking sheet and coat the wells and the top of the pan with cooking spray. set aside.
Combine 1/3 cup of the panko, 1/3 cup of the Parmesan, and 1 tablespoon olive oil in a bowl . Set aside.
Place the egg in a large bowl and beat it with a fork. Add the remaining 1/2 cup panko, 2/3 cup Parmesan, chicken, onion, basil, garlic, salt, oregano, and pepper. Using clean hands, mix everything until combined. Don’t squeeze or overwork the mixture.
Divide the mixture among the wells of the muffin pan. Evenly divide the mozzarella among the muffins. Push the cheese into the center of the chicken mixture, making sure to enclose the cheese in the chicken mixture. Smooth out the tops of the muffins.
Sprinkle the panko-parmesan mixture over the tops of the muffins, gently pressing to adhere.
Place the baking sheet with the muffin pan on it in the oven and bake until the meatloaf muffins are cooked through, about 25 minutes.
While the muffins cook, heat the marinara sauce and keep it warm.
While the muffins cook, heat the frozen green beans according to package instructions.
When the muffins are done cooking, set the oven to broil and broil until the panko topping is golden brown, about 2-3 minutes. Remove the baking sheet to a wire rack and let cool for 5 minutes. Run a small knife around the perimeter of each well to loosen and remove the meatloaf muffins. Serve immediately with the marinara sauce and green beans.