Preheat oven to 375°F (190°C).

In a large bowl, combine the ground beef, milk, breadcrumbs, onions, eggs, black pepper, salt, garlic powder, and brown sugar. Mix until just combined — don’t overwork it.

Shape the mixture into a loaf and place it in a baking dish or on a parchment-lined sheet pan.

Spread ¾ cup of the ketchup over the top of the loaf, reserving the rest for later.

Bake for 45–55 minutes, or until the internal temperature reaches 160°F (71°C).

In the last 5 minutes of baking, spread the remaining ketchup on top and let it caramelize slightly.

Let rest for 10 minutes before slicing.