In a bowl, combine ground beef, breadcrumbs, egg, onion, garlic, salt, and pepper. Mix gently—overworking the meat makes tough patties. Shape into four oval patties (about 1⁄2-inch thick).

Heat olive oil in your skillet over medium-high heat. Add patties and cook for 4–5 minutes per side until browned. Transfer them to a plate (they won’t be fully cooked yet—that’s okay!).

In the same skillet, add mushrooms and cook for 3–4 minutes until softened. Sprinkle flour over them and stir for 1 minute to cook off the raw taste. Slowly pour in beef broth, whisking constantly to avoid lumps.

Stir in Worcestershire sauce, thyme, salt, and pepper. Bring the gravy to a simmer, then return the patties to the skillet. Cook for 8–10 minutes, flipping halfway, until the patties are cooked through and the gravy thickens.