Slice the onion into thin half-moons and measure all remaining ingredients before you begin cooking.

In a large bowl, gently combine ground beef, breadcrumbs, egg, Worcestershire sauce, garlic powder, onion powder, salt, and pepper until just blended.

Divide the mixture into 4 equal portions and shape each into an oval patty about 3/4 inch thick; press a small dimple in the center of each patty.

Heat a large cast-iron or heavy skillet over medium-high heat. Add 1 tablespoon of oil and sear the patties for 4–5 minutes per side, or until browned and the internal temperature reaches 160°F (71°C). Transfer patties to a plate, tent with foil, and let rest.

Reduce heat to medium, add butter to the same skillet, and sauté the sliced onions for 8–10 minutes until golden and softened, stirring occasionally.

Sprinkle flour over the onions and cook, stirring constantly, for 1 minute to eliminate the raw flour taste.

Slowly whisk in beef broth and 1 tablespoon Worcestershire sauce, scraping up browned bits from the pan. Bring to a gentle simmer and cook for 3–4 minutes until the gravy thickens.

Season gravy with salt and pepper to taste, return the rested patties to the skillet, spoon gravy over the top, and simmer for 2 minutes to heat through. Garnish with fresh thyme if desired and serve immediately.