Preheat oven to 375°F (190°C) and grease a 12-cup muffin tin.
In a large bowl, mix ground beef, egg, breadcrumbs, ketchup, milk, onion, garlic powder, Worcestershire sauce, salt, and pepper. Avoid overmixing.
Evenly distribute the meat mixture in muffin cups, shaping gently. Top each with ketchup.
Bake for 20-25 minutes, until cooked through (internal temperature of 160°F or 71°C).
Let stand for 5 minutes before removing from the tin.
Serve warm with additional ketchup or barbecue sauce.
Enjoy your Mini Meatloaf Muffins with your favorite sides for a cozy and satisfying meal!