Preheat your oven to 200°C (400°F). Line a baking sheet with foil.

In a skillet, add olive oil and sauté onion and garlic until fragrant and soft, about 3 to 5 minutes.

In a large bowl, combine ground chicken, cooled onion-garlic mixture, breadcrumbs, milk, Parmesan, egg, parsley, Italian seasoning, and salt. Mix gently.

Form about two-thirds of the mixture into a loaf on the baking sheet and create a well in the center for mozzarella.

Fill the well with mozzarella cheese strings, cover with remaining mixture.

Spread marinara sauce over the top of the meatloaf.

Bake in the preheated oven for about 45 minutes until golden brown and cooked through.

While baking, mix melted butter with panko and Parmesan for topping.

After 45 minutes, add shredded mozzarella and panko mixture on top. Bake for an additional 15 to 20 minutes until crispy.

Let the meatloaf rest for 10 minutes before slicing.