In a large mixing bowl, combine the ground beef, bread crumbs, milk, egg, finely chopped onion, minced garlic, salt, and black pepper. Mix gently until well incorporated, about 2-3 minutes.

Transfer the meat mixture to a loaf pan. Shape into a uniform loaf about 2 inches high. Use a spatula to smooth the sides if necessary.

Whisk together the ketchup, brown sugar, and mustard in a separate bowl. Spread half of the glaze over the top of the shaped meatloaf and reserve the remaining.

Preheat your oven to 350°F (175°C). Bake the meatloaf for 50-60 minutes, or until the internal temperature reaches 160°F (70°C). About 10 minutes before it's done, brush the remaining glaze on top.

Remove from the oven and let the Glazed Meatloaf rest for 10 minutes before slicing. Serve warm with your favorite sides.