Combine beef, onion, cracker crumbs, Worcestershire and egg in a large bowl. Mix well with hands or a spoon.
Shape meat into 6 rectangular mini meatloaves, each about the size of a deck of cards (3-1/2 by 2x1/2 by 1/2-inch thick).
Heat oil in a wide skillet over medium-high heat; brown meatloaves 3 to 4 minutes per side. Remove from pan and set aside. Drain fat from pan.
Add sauce and brown sugar to pan. Bring to a boil; reduce heat and simmer over medium heat 3 minutes, stirring frequently until slightly reduced. Return meatloaves to pan and spoon sauce over tops. Simmer, uncovered, over medium heat 5 minutes or until cooked through. Serve meatloaves and sauce with mashed or roasted potatoes, if desired.