Preheat the griddle to 350*F (176*C) or medium-high heat.
Season the beef with salt and pepper.
Slice the buns in half and lightly toast the buns on the griddle, reserve, and hold warm.
Put down butter and let it start melting.
Put the burger puck down on top of the butter, place a small piece of parchment paper down, and then smash with a press to flatten out to 1/8″ or less.
Cover the patties with sliced onions and let them cook for 1-2 minutes
Scrape each patty off the griddle and flip them.
Cut each piece of cheese in half and place an “X” on each smash burger patty.