In a large bowl, combine ground beef with black pepper, salt, garlic powder, worcestershire sauce, garlic, bread crumbs and 1 large egg.
Form into 4-6 oval or circular patties.
In a large non-stick skillet, melt 2 tablespoons butter over medium high heat.
Add the patties to the pan and cook for about 4 minutes, then flip and continue cooking until the patties are cooked through.
Remove the patties from the pan, cover with foil and set aside.
Drain off any excess grease in the pan.
Over medium-low heat, add the onions and mushrooms to the pan and cook for 15-20 minutes, or until the mushrooms and onions are tender and golden brown.
Sprinkle 2 tablespoons flour over the onions, stir, and allow the flour to cook for a minute or two, then stir in 1 tablespoon ketchup, 2 teaspoons Worcestershire sauce and 2 cups beef broth. Bring to a boil, then reduce heat to low. Add the Salisbury Steak patties back to the pan and simmer for about 15 minutes, or until the gravy has thickened.
Serve over egg noodles.