Preheat your oven to 375°F (190°C). Lightly grease a standard loaf pan or line it with parchment paper for easy removal.
In a large mixing bowl, combine the ground beef, panko breadcrumbs, chopped onion, beaten eggs, milk, Worcestershire sauce, Dijon mustard, smoked paprika, garlic powder, salt, and pepper. Gently mix with your hands until just combined. Be careful not to overmix, as this can lead to a tough meatloaf.
Transfer the meat mixture into the prepared loaf pan and shape it into an even loaf.
In a small bowl, whisk together the ketchup, maple syrup, apple cider vinegar, and liquid smoke (if using) until smooth. This is your smoky maple glaze.
Spread about half of the glaze evenly over the top of the meatloaf.
Bake for 45 minutes. After 45 minutes, remove the meatloaf from the oven and spread the remaining glaze over the top. This ensures a beautiful, caramelized finish.
Return the meatloaf to the oven and continue baking for another 15-20 minutes, or until the internal temperature reaches 160°F (71°C) on a meat thermometer.
Once cooked, let the meatloaf rest in the pan for 10-15 minutes before slicing and serving. This allows the juices to redistribute, ensuring a moist and tender result.