01 - Divide the ground beef into 4 equal portions and loosely roll into balls without packing tightly
02 - Heat a large cast-iron skillet or griddle over high heat until very hot
03 - Place beef balls on hot skillet and firmly smash down with heavy spatula or burger press until about 1/2-inch thick
04 - Season immediately with salt and pepper, cooking without moving for 2-3 minutes until edges are deeply browned and crispy
05 - Flip burgers, top each patty with cheese slice, cook 1-2 minutes more until cheese melts and burgers are cooked through
06 - While burgers cook, melt butter in separate skillet or on griddle, toast buns cut side down until golden brown
07 - Spread burger sauce on bottom buns, layer lettuce, tomato, onion, add smash patties, add pickles if desired, cover with top bun
08 - Serve immediately while hot