01 -
Heat the oven to 350°F and grease a 9-by-13-inch baking dish. Have the sauce ingredients ready before browning the meat.
02 -
Gently combine beef, breadcrumbs, egg, garlic powder, onion powder and seasoning. Shape four to six oval patties of similar thickness.
03 -
Brown patties in a skillet over medium heat, about 2–3 minutes per side as a starting estimate. Work in batches if necessary and transfer directly to the baking dish; do not interrupt cooking to refrigerate partially cooked meat.
04 -
Whisk condensed soup, milk and Worcestershire sauce. Pour around the patties and distribute thin onion slices and optional mushrooms over them.
05 -
Cover with foil and bake about 30–35 minutes, then uncover as needed to finish the sauce. Check every patty for at least 160°F; extend cooking if necessary rather than relying on bubbling gravy.
06 -
Serve with optional parsley after verifying doneness. Cool leftover portions promptly under the storage guidance above.