Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the ground beef, breadcrumbs, milk, grated onion, eggs, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Use your hands to mix gently but thoroughly until everything is just combined. Overmixing can make the patties tough. Form the mixture into 6-8 oval-shaped patties, about 3/4-inch thick.
Heat the vegetable oil in a large skillet over medium-high heat. Once the oil is shimmering, add the patties in batches, being careful not to crowd the pan. Brown them for about 3-4 minutes per side, just until a nice crust forms. They do not need to be cooked through. This step is non-negotiable for developing deep flavor. Transfer the browned patties to a 9x13 inch baking dish.
In a medium bowl, whisk together the cream of mushroom soup, French onion soup, and water or beef broth until smooth. This creates the gravy base. Pour this mixture evenly over the browned patties in the baking dish, making sure each one gets coated.
Cover the baking dish tightly with aluminum foil. Place it in the preheated oven and bake for 45 minutes. The foil trap creates a steamy environment that gently cooks the patties, making them incredibly tender. After 45 minutes, carefully remove the foil and bake for an additional 15 minutes to allow the gravy to thicken slightly and the top to get a beautiful glazed look.
Remove the dish from the oven and let it rest for 5-10 minutes. This allows the juices to redistribute, making the patties easier to serve. Spoon the abundant, savory gravy over each patty. Serve hot over mashed potatoes, egg noodles, or rice, garnished with fresh parsley if desired.