Divide the ground beef into three equal pieces, roughly 3 oz (85g) each, rolling them into balls.

Place each ball between two sheets of parchment paper and use the flat side of a mallet to create thin patties.

For the sauce, stir together mayonnaise, sour cream, ketchup, mustard, and a sprinkle of black pepper until blended. Chill until ready to use.

Heat a cast iron skillet or griddle over medium-high heat.

Season one side of the patties with salt and pepper. Place the seasoned side down onto the hot surface, then season the other side similarly.

Cook for 1-2 minutes before flipping.

Top one patty with cheese and stack another patty on top, cooking for an additional 30 seconds to a minute.

Remove the stack from the heat.

Toast the brioche buns on the grill for about 30 seconds.

Spread some sauce on the bottom bun, layer with lettuce, tomato, and onion, then place the double cheesed patties on top.

Add pickles, more sauce, and cap it with the top bun.

Enjoy your creation!