Preheat the oven to 400°. Bake the bacon on a broiler pan or rack-lined baking sheet until the fat is partially rendered, about 15 minutes. Baste the bacon with the maple syrup; bake until crisp, 5 to 6 minutes.
Heat a cast-iron skillet over medium-high heat. In a bowl, combine the beef, Worcestershire and onion (grate the onion over the bowl so the juices fall into the meat). Stir in the mustard; season with salt and lots of pepper. Form into 4 patties (thinner at the center and thicker at the edges). Drizzle the patties with oil; cook, flipping once, until a nice crust forms, about 7 minutes. Top with the cheese and cook for about 2 minutes to melt.
Brush a nonstick skillet over medium heat with some melted butter. Add the eggs and fry to your liking; season.
Toast the buns, basting with melted butter. Top the bun bottoms with the burgers, bacon, eggs and bun tops