In a skillet, heat a splash of olive oil over medium heat. Sauté the finely diced onion and minced garlic for about 5 minutes, or until they're softened and fragrant. Once done, remove them from heat and allow to cool completely before mixing with the other ingredients in the Parmesan Chicken Meatloaf.

In a large mixing bowl, combine the cooled onion and garlic mixture with ground chicken, seasoned breadcrumbs, milk, Parmesan, and egg. Add chopped fresh parsley, Italian seasoning, and salt. Mix gently with your hands until just combined.

Prepare a lined baking sheet and spread about two-thirds of the meat mixture into a loaf shape, creating an indentation down the center for the mozzarella. Carefully cover the cheese with the remaining meat mixture.

Preheat your oven to 200°C (400°F). Spread marinara sauce evenly over the top of the shaped meatloaf, then bake for 45 minutes, or until the meatloaf is cooked through.

To add the topping, mix together panko breadcrumbs, Parmesan, melted butter, and optional parsley. Sprinkle this mixture over the meatloaf, then return to the oven for an additional 15-20 minutes.

Once cooking is complete, allow the meatloaf to rest for 10 minutes before slicing and serving.