In a large bowl, combine ground beef, breadcrumbs, milk, chopped onion, salt, black pepper, allspice, nutmeg, garlic powder, and egg. Mix well.
Shape the mixture into small meatballs.
In a large skillet, melt butter over medium heat. Add meatballs and cook until browned on all sides. Remove meatballs from skillet and set aside.
In the same skillet, add flour and cook, stirring constantly, for 1 minute. Gradually whisk in beef broth, heavy cream, and Worcestershire sauce. Cook until the sauce thickens.
Return the meatballs to the skillet and simmer for an additional 10 minutes, until cooked through.
Season with salt and pepper to taste.
Serve the meatballs and gravy over mashed potatoes or egg noodles, garnished with chopped fresh parsley.