Gather the ingredients. Preheat the oven to 350 degrees F (180 degrees C) and line a loaf pan with parchment paper or foil.

Place ground chicken in a large mixing bowl. Add onion, garlic, egg, ¼ cup parsley, ½ cup marinara, Italian-seasoned bread crumbs, ⅓ cup Parmesan, Italian seasoning, and salt and pepper, to taste. Mix, using hands to combine ingredients. Add chicken mixture to the prepared pan, and shape gently into a loaf.

Bake in the center of the preheated oven for 45 minutes.

Remove loaf from the oven and brush with ¼ cup marinara. Sprinkle mozzarella evenly on the top.

Bake for 15 minutes more. Allow to cool on a rack for about 10 minutes.

Meanwhile, melt butter in a skillet over medium heat. When butter stops sizzling, add panko and garlic powder. Cook, stirring frequently, until panko is lightly toasted, 3 to 4 minutes. Remove from the heat and allow to cool, 4 to 5 minutes.

Stir in remaining 2 tablespoons Parmesan cheese, and remaining 1 tablespoon minced parsley.

Plate the meatloaf, top with Parmesan and panko mixture. Serve with remaining marinara sauce and garnish with parsley sprigs or other fresh herbs, if desired.