Preheat your oven to 375°F (190°C).

In a large mixing bowl, combine ground beef, breadcrumbs, milk, egg, finely chopped onion, salt, and black pepper. Mix gently until combined.

Shape the mixture into a loaf form, about 8-10 inches long, and place in a greased baking dish or loaf pan.

In a small bowl, whisk together the ketchup, brown sugar, and Worcestershire sauce until smooth.

Spread half of the glaze over the top of the meatloaf.

Bake the meatloaf for 45 minutes.

Check the internal temperature, which should be 160°F (71°C). If not reached, continue baking for an additional 5–10 minutes.

Once at the desired temperature, spread the remaining glaze on top and bake for an additional 15 minutes.

Let the meatloaf rest for 10 minutes before slicing.