Slice the large yellow onion into ½-inch thick rounds. In a skillet, heat olive oil over medium-low heat, adding onion slices along with Worcestershire sauce, Creole seasoning, and a sprinkle of brown sugar. Cook for about 20 minutes until golden brown and caramelized.

Mix ground beef with additional Creole seasoning and form into thin patties (¼-inch thick). Sear the patties for 2-3 minutes on each side, adding a slice of cheese on top just before removing from heat.

In a mixing bowl, combine mayonnaise, relish, Dijon mustard, sugar, garlic powder, onion powder, smoked paprika, and cayenne pepper. Whisk until smooth and set aside.

To assemble, place a slice of caramelized onion as the base, add a cheesy beef patty, drizzle with sauce, and top with another slice of onion.