In a large bowl, combine ground beef, salt, pepper, garlic powder, onion powder, egg, breadcrumbs, and Worcestershire sauce. Mix until well combined.

Divide the mixture into 4 equal parts and shape each into a flat patty.

Heat olive oil in a skillet over medium heat. Add patties and cook for about 4-5 minutes on each side or until browned. Remove the patties and set aside.

In the same skillet, add sliced onions and cook until soft. Sprinkle flour over the onions and stir to combine. Gradually add beef broth, stirring continuously, until the mixture thickens into a gravy.

Return the patties to the skillet, spooning the gravy over them. Cover and simmer for about 7-10 minutes or until the patties are cooked through. Serve warm with fresh parsley on top.