In a large bowl, combine ground beef, breadcrumbs, egg, milk, chopped onion, 2 tablespoons ketchup, Worcestershire sauce, salt, and pepper. Mix gently until just combined. Do not overmix.
Shape the mixture into a loaf and place it in a baking dish or on a foil-lined baking sheet.
In a small bowl, whisk together the glaze ingredients: 0.5 cup ketchup, brown sugar, and Dijon mustard.
Spread the glaze evenly over the top of the meatloaf.
Bake for 60 minutes, or until the internal temperature reaches 160°F (71°C).
Let the meatloaf rest for 10 minutes before slicing and serving.
Notes
Serve with mashed potatoes and your favorite vegetables for a complete meal.