Divide the ground beef into 8 loosely packed balls, about 4 ounces each.

Preheat a cast-iron skillet, flat-top griddle, or heavy pan over high heat until very hot.

Mix together the mayonnaise, ketchup, mustard, pickle relish, and garlic powder to make the burger sauce.

Lightly butter and toast the burger buns until golden brown.

Place the beef balls onto the hot cooking surface.

Using a sturdy spatula or burger press, firmly smash each ball into a thin patty.

Season the patties with salt and pepper immediately after smashing.

Cook for about 2 minutes until crispy edges form and a deep brown crust develops.

Flip the patties and immediately place a slice of cheddar cheese on top.

Cook for another 1 to 2 minutes until the cheese melts completely.

If making double burgers, stack two patties together.

Spread burger sauce onto the toasted buns.

Layer the patties onto the buns and top with bacon, onions, pickles, tomatoes, and lettuce.

Serve immediately while hot and juicy.