Preheat your oven to 375°F (190°C). Lightly grease a baking sheet or a 9x5 inch loaf pan.

In a large mixing bowl, whisk together the egg, minced garlic, finely chopped onion, Worcestershire sauce, and Italian seasoning, salt, and pepper.

Add the ground chicken, Panko breadcrumbs, and grated Parmesan cheese to the bowl. Use your hands to gently combine the ingredients until they are just mixed. Do not overwork the mixture.

Transfer the mixture to your prepared baking sheet and form it into a loaf shape (approximately 9x5 inches), or press it evenly into the loaf pan.

In a small bowl, mix together the ketchup, brown sugar, and apple cider vinegar to create the glaze.

Spread half of the glaze evenly over the top and sides of the meatloaf. Place it in the preheated oven and bake for 30 minutes.

Remove the meatloaf from the oven, spread the remaining glaze on top, and return it to the oven. Bake for an additional 15-20 minutes, or until an instant-read thermometer inserted into the center reads 165°F (74°C).

Let the meatloaf rest for at least 10 minutes before slicing and serving. This allows the juices to settle, ensuring a moist result.