Make the steak patties:
In a large mixing bowl, combine ground beef, breadcrumbs, egg, Worcestershire sauce, garlic, onion powder, ketchup (if using), salt, and black pepper. Mix until just combined—don’t overwork the meat.
Divide the mixture into 4 equal portions and shape into oval patties about 1/2-inch thick.

Cook the patties:
Heat a large skillet over medium heat and add a tablespoon of oil or butter. Cook the patties for 4-5 minutes on each side until browned. Remove them from the skillet and set aside (they don’t need to be fully cooked yet).

Make the mushroom gravy:
In the same skillet, melt 2 tablespoons of butter. Add sliced onions and mushrooms, and cook until softened, about 5-7 minutes.
Stir in the flour and cook for 1 minute to eliminate the raw taste.
Slowly pour in the beef broth while stirring, then add Worcestershire sauce, Dijon mustard (if using), and season with salt and pepper. Let the gravy simmer until it thickens, about 3-4 minutes.

Simmer the steaks:
Return the cooked patties to the skillet, cover them with gravy, and reduce heat to low. Simmer for 10-15 minutes, or until the steaks are cooked through and the flavors meld together.

Serve:
Garnish with freshly chopped parsley and serve hot with mashed potatoes, rice, or buttered noodles.