In a skillet over medium heat, add the bacon slices and cook until crispy, about 6–8 minutes. Transfer the bacon to paper towels to absorb excess grease.

Remove excess bacon grease from the skillet, keeping a thin layer. Add the sliced onions and cook for 10–15 minutes until caramelized. Pour in Irish stout and simmer until reduced by half, seasoning with salt and pepper.

In a mixing bowl, combine ground beef with Worcestershire sauce, salt, and pepper. Shape into four patties slightly larger than the buns.

Heat the skillet or grill to medium-high. Cook patties for 3–4 minutes per side until desired doneness. Top each patty with cheddar cheese during the last minute to melt.

In a small bowl, combine sour cream and Dijon mustard with salt. Mix until smooth and set aside.

In the skillet, add butter and toast the brioche buns until golden brown, about 2–3 minutes.

Layer the burger: bottom bun, beef patty with cheese, caramelized onions, crispy bacon, and drizzle with sauce before adding the top bun.

Serve hot, inviting friends and family to enjoy. Pair with fries or a cold pint of stout.