Preheat the oven to 350 degrees.
Line a baking pan with foil.
Place a baking rack over the foil and spray with cooking spray.
Season the outside of each of the hamburger steaks with the salt, pepper, onion powder and garlic powder to your preference.
Place the hamburger patties on top of the baking rack. Bake for 15-25 minutes until the the juices from the patties are clear.
In the meantime, melt the bacon grease or oil in a large skillet over medium heat.
Add the mushrooms and onions. Sauté until the vegetables are tender about 10 minutes.
Add the flour and stir until the flour is incorporated and there are no lumps.
Add the beef broth. Continue to simmer for 3-5 minutes until the broth begins to thicken into a gravy.
Season the gravy with additional salt and pepper if needed.
To serve, spoon the gravy over the tops of the hamburger steaks.