In a large bowl, combine the ground beef, breadcrumbs, milk, chopped onion, egg, garlic powder, Worcestershire sauce, salt, and pepper. Mix until just combined. Shape into 4 oval patties, about 1/2 inch thick.

1. Heat 1 tablespoon of olive oil or butter in a large skillet over medium heat. Add the patties and cook for 4-5 minutes on each side until browned and cooked through. Transfer to a plate and set aside.
2. In the same skillet, add the remaining tablespoon of oil or butter. Add the sliced onion and cook for 3-4 minutes until softened. Add the sliced mushrooms and cook for an additional 5 minutes until tender and releasing their moisture.
3. Sprinkle the flour over the mushrooms and onions, stirring to combine. Cook for 1-2 minutes. Gradually add the beef broth, Worcestershire sauce, and soy sauce (if using), stirring constantly. Bring to a simmer and cook for 3-5 minutes until the gravy thickens.
4. Return the patties to the skillet, spooning the gravy over them. Reduce heat to low and simmer for an additional 5-10 minutes, allowing the flavors to meld and the patties to absorb some of the gravy.
5. Serve with mashed potatoes, rice, or your favorite side dishes, spooning gravy over the patties.