In a large bowl, combine the ground beef, breadcrumbs, Parmesan cheese, onion, parsley, egg, garlic powder, onion powder, salt, pepper, and Worcestershire sauce. Mix until well combined.
Form the mixture into 12 equal-sized patties (rissoles).
Heat olive oil in a large skillet over medium heat. Cook the rissoles for about 5-6 minutes on each side, or until they are browned and cooked through. Remove from the skillet and set aside.
In the same skillet, melt the butter over medium heat. Add the sliced mushrooms and cook until they are browned and tender, about 5 minutes.
Sprinkle the flour over the mushrooms and stir to combine. Gradually add the beef broth and soy sauce, stirring constantly until the mixture thickens. Season with thyme, salt, and pepper to taste.
Return the rissoles to the skillet, spoon the mushroom gravy over them, and simmer for an additional 5 minutes to heat through.
Serve warm.