In a large skillet, heat olive oil over medium heat. Add the finely diced onion and cook until softened, about 5-7 minutes. Stir in minced garlic and cook for another minute. Remove from heat and let cool slightly.

In a large mixing bowl, break up the ground chicken. Add the onion and garlic mixture, egg, panko breadcrumbs, Parmesan cheese, parsley, Italian seasoning, salt, and black pepper.

Using clean hands, mix all ingredients until just combined. Avoid overmixing to prevent a tough texture.

Lightly grease a 9x5 inch loaf pan. Transfer the chicken mixture to the pan and press it down evenly, shaping it into a loaf.

Preheat your oven to 375°F (190°C). Bake the loaf for 30 minutes.

If using, prepare the glaze by whisking together ketchup, Dijon mustard, and optional brown sugar/maple syrup. After 30 minutes, spread the glaze over the loaf and bake for an additional 20-30 minutes, until the internal temperature reaches 165°F (74°C).

Let the meatloaf rest for 10 minutes before slicing and serving.