01 -
In a bowl, blend together ketchup, mayo, Worcestershire, and relish.
02 -
Melt butter and stir onions for 15-20 minutes until golden and sweet.
03 -
Season the ground beef and press out 4 thin patties.
04 -
Brown the patties for 3-4 minutes on each side.
05 -
Spread butter on bread, stack with cheese, meat, and onions.
06 -
Toast the sandwiches on both sides for 2-3 minutes until gooey inside.