Combine ground beef, salt, pepper and garlic powder in a medium bowl. Divide meat into 6 even portions and form into patties.
In a large skillet over medium heat cook patties 6-12 minutes per side until internal temperature reaches your desired doneness. When they are done to your liking, remove the steaks and add onions to the pan, cooking for 6 minutes. Add garlic and cook 1 minute. Add flour and cook 2 minutes, stirring constantly. Gradually add broth and Worcestershire sauce. Stir until smooth. Reduce to half, stirring occasionally, about 15 minutes. Return patties to skillet and heat through.
To serve place hamburger steaks on plate. Whisk in butter, quickly, and spoon gravy and onions over patty. Sprinkle with chopped parsley.