Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the ground beef, bread crumbs, onion, milk, beaten egg, 2 tablespoons of ketchup, Worcestershire sauce, parsley, salt, garlic powder, and black pepper. Blend these ingredients using your hands until thoroughly incorporated, ensuring a consistent mixture.
Transfer the meat mixture into a loaf pan and press it down evenly, forming a compact layer.
In a smaller bowl, stir together 1/4 cup of ketchup, brown sugar, and red wine vinegar until smooth. Spread this sauce evenly over the top of the meatloaf.
Place the loaf pan in the preheated oven and bake, uncovered, for approximately 55 minutes, until fully cooked through.
Once baking is complete, allow the meatloaf to rest for 8-10 minutes before slicing and serving to maintain its structure and retain moisture.