Cook the bacon in a large skillet over medium heat until crispy, about 8-10 minutes. Transfer to a plate and leave drippings in the skillet.

Caramelize the onions in the leftover bacon grease over medium heat for 10-15 minutes until golden brown.

Add the Irish stout to the caramelized onions, increase heat and simmer for about 5 minutes until thickened. Season with salt and pepper.

In a mixing bowl, combine ground beef, Worcestershire sauce, salt, and pepper. Form into four patties.

Cook the patties on a preheated grill or skillet for 3-4 minutes on each side, topping with cheese during the last minute.

Mix sour cream, Dijon mustard, and salt in a small bowl to create the sauce.

Melt butter in another skillet and toast brioche buns cut-side down until golden brown.

Assemble the burgers: bottom bun, patty with cheese, caramelized onions, bacon, and sauce on top bun.

Serve hot with sides like sweet potato fries or rustic chips.