Preheat your oven to 200°C (400°F) and line a baking sheet with foil for easy cleanup.

In a medium skillet, add olive oil over medium heat. Add diced onion and minced garlic, sauté for about 3–5 minutes until softened.

In a large mixing bowl, combine ground chicken, cooled onions, garlic, seasoned breadcrumbs, milk, Parmesan cheese, and egg. Add parsley, Italian seasoning, and salt. Mix gently.

Shape two-thirds of the meat mixture into a loaf on the baking sheet, creating a well in the center for the mozzarella.

Cover the mozzarella with the remaining meat mixture, sealing it well.

Spoon marinara sauce over the meatloaf before baking.

Bake for 45 minutes until golden brown.

Prepare the topping by mixing melted butter, panko breadcrumbs, grated Parmesan, and parsley.

After 45 minutes, remove the meatloaf and top with mozzarella and the panko mixture. Bake another 15–20 minutes.

Let the meatloaf rest for 10 minutes before slicing.