Divide beef into 8 (2-oz.) patties. Very loosely form into a ball, making sure to not tightly pack together.
STEP 2
Heat an ungreased griddle or large cast-iron skillet over high heat until very hot. Working in batches as needed, place patties on hot skillet. Using a large spatula, immediately smash patties down flat and thin; season with salt and pepper. Cook until edges start to crisp, about 1 minute. Flip, season with salt and pepper, and cook until other side is browned, about 30 seconds.
STEP 3
Top patties with a slice of cheese and continue to cook until cheese melts, about 20 seconds more.
STEP 4
Serve double-stacked on buns with desired toppings.