Preheat your oven to 400°F (200°C). Coat a standard 12-cup nonstick muffin pan thoroughly with cooking spray, making sure each cup is evenly greased.
Set aside 1 tablespoon of Romano or Parmesan cheese for the finishing touch. In a large mixing bowl, combine the ground chicken, kosher salt, black pepper, garlic powder, onion powder, 1/2 cup grated Romano or Parmesan cheese, seasoned bread crumbs, and egg.
Mix the ingredients gently until evenly combined. Avoid overmixing or compacting the chicken mixture, as this can create a dense texture. If the mixture feels unusually dry, add 1–2 tablespoons of water as needed.
Divide the prepared chicken mixture evenly among the 12 muffin cups. Gently press each portion into its cup and smooth the tops to create uniform shapes. Do not pack the mixture too firmly.
Place the muffin pan in the preheated oven and bake for 20 minutes. During this first stage, the chicken meatloaf muffins will begin to firm up and hold their shape.
Carefully remove the muffin pan from the oven. Spoon approximately 1 tablespoon of marinara sauce over each meatloaf muffin, spreading it evenly across the surface.
Top each muffin with approximately 1 tablespoon of shredded mozzarella cheese. Return the pan to the oven and bake for another 10 minutes, or until the mozzarella has melted and the chicken is fully cooked.
Remove the muffin pan from the oven and sprinkle the reserved tablespoon of Romano or Parmesan cheese over the tops. Allow the muffins to rest in the pan for 5 minutes before carefully removing them.
Finish with chopped fresh parsley and garnish with fresh basil leaves. Serve warm with additional marinara sauce on the side, if desired.