Preheat oven to 350 degrees F (175 degrees C).
In a large bowl, combine the beef, egg, onion, milk and bread OR cracker crumbs. Season with salt and pepper to taste and place in a lightly greased 9x5-inch loaf pan, or form into a loaf and place in a lightly greased 9x13-inch baking dish.
In a separate small bowl, combine the brown sugar, mustard and ketchup. Mix well and pour over the meatloaf.
Bake at 350 degrees F (175 degrees C) for 1 hour.
Per Serving: 372 calories; protein 18.2g; carbohydrates 18.5g; fat 24.7g; cholesterol 98mg; sodium 334.6mg.