Preheat a cast-iron skillet or griddle over medium-high heat
Form ground beef into loose balls, about 2 to 3 ounces each
Season the beef balls lightly with salt and pepper
Lightly butter or oil the cooking surface if needed
Place the beef balls on the hot surface
Smash each ball flat with a sturdy spatula or burger press
Hold the smash for a few seconds to create a thin patty
Cook until the edges are browned and crisp, about 2 minutes
Flip the patties once
Add cheese immediately after flipping if desired
Cook the second side for about 1 minute
Toast the buns on the skillet if desired
Assemble the burgers with your preferred toppings and sauce
Serve immediately