01 -
Heat olive oil and butter in a large pan over medium heat. Add sliced onions and cook, stirring occasionally, until golden brown and soft, about 25–30 minutes. Add bourbon, brown sugar, salt, and pepper. Cook for 2 minutes or until the bourbon has reduced and the onions are glossy. Set aside.
02 -
Preheat a grill or skillet to medium-high heat. In a bowl, gently mix ground beef with salt, pepper, and Worcestershire sauce. Form into 4 equal patties, making a small indentation in each center. Grill or pan-fry for 4–5 minutes per side, or until desired doneness. Place a slice of cheddar cheese on each patty during the last minute to melt.
03 -
In a separate pan, cook bacon over medium heat until crisp. Transfer to paper towels to remove excess fat.
04 -
Lightly butter the brioche buns and toast on a grill or skillet, cut side down, until golden and crisp.
05 -
Spread ketchup, mustard, or chosen sauce on the bottom bun. Place the cheeseburger patty atop. Layer with crispy bacon, then a generous spoonful of caramelized onions. Add lettuce and tomato if using. Cap with the top bun and press gently.
06 -
Serve immediately with accompaniments such as fries or a crisp salad.