Divide the beef into three equal portions and shape into patties. Sprinkle on both sides with the salt and pepper.
Butter the inside faces of the buns.
Heat a 12-inch cast iron skillet over medium for two minutes.
Place buns buttered sides down and toast for a few minutes, until light golden brown on the undersides.
Transfer buns to serving plates and raise heat to medium-high.
Place patties onto skillet and use a sturdy metal spatula to firmly smash each one until it grows in diameter by about an inch. After this, absolutely ignore the burgers for about three minutes, until the undersides are brown and crisp at the edges and any juices on the surface are hot and bubbly.
Flip each burger and top with one ounce of the cheddar.
Cover skillet and continue cooking for another minute or two, until cheese is almost melted.
Remove from heat and place burgers onto buns.
Stack each burger with two slices tomato, three pickle chips, and one leaf lettuce, torn to fit, if necessary.
Divide ketchup, mustard, and mayo among top buns and spread to the edges. Close each burger and serve right away.