Preheat your oven to 200°C (400°F). Line a baking sheet with aluminum foil and lightly coat it with cooking spray.

In a skillet, heat a drizzle of olive oil over medium heat. Add the finely diced onion and minced garlic, cooking until translucent, about 3–5 minutes.

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

Form two-thirds of the meat mixture into a rectangular shape on the baking sheet. Create a well in the center and add the mozzarella cheese strings. Mold the remaining mixture over the cheese to seal.

Spread marinara sauce over the top of the meatloaf for flavor and moisture.

Bake the meatloaf for 45 minutes until edges are crispy and the center is firm.

Combine panko breadcrumbs, Parmesan cheese, melted butter, and parsley in a bowl to create a topping.

After 45 minutes, sprinkle the breadcrumb mixture on top and return to the oven for an additional 15–20 minutes until golden brown.

Let the meatloaf rest for 10 minutes before slicing to allow juices to redistribute.