In a large bowl, combine the ground beef, breadcrumbs, chopped onion, egg, garlic powder, Worcestershire sauce, salt, and pepper. Mix until just combined—avoid overmixing to keep the patties tender.
Form the mixture into 4 oval patties.
Cook the Hamburger Steaks:
In a large skillet, heat the olive oil over medium-high heat. Add the hamburger steaks and cook for about 4-5 minutes on each side until browned and cooked through. Remove the patties from the skillet and set aside.
Make the Onion Gravy:
In the same skillet, add the butter and sliced onions. Sauté for about 5-7 minutes until the onions are caramelized and golden brown.
Sprinkle the flour over the onions and stir to combine. Cook for an additional minute.
Gradually pour in the beef broth and Worcestershire sauce, stirring constantly to avoid lumps. Bring the mixture to a simmer and cook until it thickens, about 3-5 minutes. Season with salt and pepper to taste.
Combine:
Return the hamburger steaks to the skillet, spooning the gravy over the patties. Simmer for an additional 2-3 minutes to heat everything through.
Serve:
Garnish with fresh parsley if desired. Serve the hamburger steaks with onion gravy over mashed potatoes, rice, or your favorite side.