In a large mixing bowl, mix the ground beef, breadcrumbs, grated onion, egg, garlic powder, onion powder, parsley, and Worcestershire sauce. Using your hands, mix until just combined. Do not over mix (or burger steaks might come out tough). 2. Form the mixture into 8 equal balls, and transfer to a plate or tray. Press gently into burger patties. Season both sides of each patty with salt and pepper. 3. Heat butter in a large, deep pan or cast iron skillet over medium heat until melted und bubbly. Working in 2 batches (as to not overcrowd the pan) add patties and brown for 3-4 minutes a side. 4. Once browned, transfer to a plate, and repeat until all patties are browned. 5. Add the sliced mushrooms to the pan, and cook 5-6 minutes, stirring very occasionally, until they have given up most of their liquid. 6. Sprinkle the flour over the mushrooms, and stir well until fully combined. 7. Reduce heat to low, and slowly whisk or stir in the beef broth until fully incorporated. 8. Add the meat patties back in a single layer. Cover and cook on low heat, 10-15 minutes. Serve wam with rice, egg noodles, or mashed potatoes.