Heat 2 tablespoons of olive oil in a skillet over medium heat. Add 1 finely diced onion and 3 minced garlic cloves, sautéing until softened, about 5 minutes. Allow to cool.

In a mixing bowl, combine 1 pound of ground chicken, cooled onion-garlic mixture, 1 cup of seasoned breadcrumbs, 1/4 cup of milk, 1/2 cup of grated Parmesan cheese, 1 egg, 2 tablespoons of chopped parsley, 1 tablespoon of Italian seasoning, and a pinch of salt. Mix gently.

On a lined baking sheet, form about two-thirds of the meat mixture into a rectangle. Create a trench down the center and fill with 1 cup of shredded mozzarella cheese. Cover with remaining meat mixture.

Spread 1 cup of marinara sauce over the meatloaf. Preheat oven to 200°C (400°F) and bake for about 45 minutes until edges brown and internal temperature reaches 74°C (165°F).

Prepare topping by mixing 1 cup of panko breadcrumbs with 1/4 cup grated Parmesan cheese, 2 tablespoons of melted butter, and 1 tablespoon chopped parsley. After 45 minutes of baking, sprinkle this topping over the meatloaf.

Return the meatloaf to the oven and bake for another 15-20 minutes until topping is golden and crispy. Allow to rest for 10 minutes before slicing.