Preheat oven to 375°F. Spray a casserole pan or glass baking dish with cooking spray.
In a medium bowl, mix together the ground beef, bread crumbs, egg, milk, Worcestershire sauce, salt and pepper. Shape into small meatballs (1 - 1 ½ inches). Place in prepared baking dish.
In a small bowl, whisk together brown sugar, ketchup, Worcestershire sauce, mustard, and vinegar. Pour sauce over meatballs.
Cover with foil and bake for 45-50 minutes or until meatballs are no longer pink inside.
Sprinkle with parsley and serve over rice, pasta or mashed potatoes.
Notes
This recipe can be doubled or tripled to prepare additional servings.