In a large mixing bowl, combine ground beef, egg, Worcestershire sauce, brown mustard, and chopped unsalted butter. Add bread crumbs, grated Parmesan cheese, and minced garlic. Mix by hand until just combined.

Shape the mixture into 4 equally sized patties, about 3/4 inch thick, and create a small indent in the center of each patty.

Preheat your grill to medium-high heat (about 400°F). Lightly oil the grill grates.

Season both sides of the patties with your choice of seasoning. Grill for 4-5 minutes without pressing down.

Flip the burgers and grill for another 3-4 minutes for medium doneness. Add cheese during the last minute.

Remove from the grill and let them rest for a couple of minutes. Serve on buns with desired toppings.