Divide the beef into 6 equal round chunks.
Place beef in a medium-high skillet and firmly flatten into a ¼" thick round patty with a metal spatula. (The patty should be larger than the bun since it will shrink while cooking)
Season liberally with salt and pepper.
Flip burger once the top begins to change color from the cooking underneath.
Season second side with salt and pepper.
While burgers are cooking butter the inside of the buns and toast lightly in separate skillet.
Placed cooked patty on a bun, top with American cheese, chopped onions,3-4 pickles, and lettuce leaf.
Place ketchup and mustard on other half of bun and top the burger.