In a small bowl, whisk all ingredients for the Special Burger Sauce. Cover and refrigerate for at least 30 minutes.

Cook bacon in a large skillet over medium heat until crispy. Remove bacon to a paper towel-lined plate. Reserve 1-2 tbsp of bacon fat in the skillet.

Divide ground chuck into 8 equal portions (3 oz each) and gently roll into loose balls. Do not flatten.

Butter the cut sides of the brioche buns and toast them in a separate pan or in the bacon skillet until golden brown. Set aside.

Heat the skillet with bacon fat over medium-high heat until very hot. Place 2-4 beef balls on the skillet.

Place a square of parchment paper over one ball and use a large, heavy spatula to smash it down firmly into a thin patty. Hold for 10 seconds. Repeat for the other balls. Remove parchment.

Season the tops of the patties generously with salt and pepper. Cook for 2-3 minutes until a deep brown crust forms.

Scrape under the patties and flip. Immediately season the new side and top each patty with a slice of cheese. (This recipe makes 4 double-patty burgers).

Cook for 1-2 minutes more until cheese is melted and gooey. If needed, cover the pan for 30 seconds to speed up melting.

To assemble: Spread a thick layer of special sauce on both buns. On the bottom bun, layer lettuce, tomato, two cheese-covered patties, and two slices of crispy bacon. Top with the other bun.

Serve immediately.