In a bowl, combine ground beef, Worcestershire sauce, salt, and pepper. Divide into 4 equal portions and shape into patties, making a slight indentation in the center.
Heat a large skillet or grill over medium-high heat. Cook patties for 4-5 minutes per side for medium doneness. During the last minute, top each patty with a slice of Swiss cheese and cover to melt.
Meanwhile, in a separate skillet, melt butter over medium heat. Add mushrooms and cook until golden and tender, about 5 minutes. Add garlic and cook 1 minute more. Season with salt and pepper.
Place each patty on a toasted bun bottom. Top with sautéed mushrooms and any desired toppings. Cover with bun tops and serve immediately.
Tips
For best results, use an instant-read thermometer: 160°F for well-done.
Toasting the buns adds texture and prevents sogginess.
Leftover cooked patties can be refrigerated for up to 3 days.