01 -
In a small dish, stir together mayo, Worcestershire, ketchup, garlic powder, salt, and pepper until smooth and creamy.
02 -
With a gentle touch, split ground beef into eight portions of 3 ounces each, lightly shaping into balls.
03 -
Get your cast iron surface blazing hot, around 450-500°F, using a stovetop or outdoor grill.
04 -
Cut out 3-inch parchment squares and have them handy for pressing patties.
05 -
Splash some oil onto the hot griddle and set up mounds of onion slices (quartered cups each).
06 -
Scatter jalapeño rings on top of each onion pile, then sprinkle a mix of salt and pepper over them.
07 -
Let the onion and jalapeño piles cook undisturbed for about 30-60 seconds until they char slightly.
08 -
Pop one ball of ground beef on each onion pile, then cover the meat with a square of parchment paper.
09 -
Use a sturdy spatula or burger press to flatten the beef into thin patties, roughly four inches wide.
10 -
Dust the flattened beef patties with the leftover salt-and-pepper blend.
11 -
Leave patties alone for 2 to 3 minutes until their edges crisp up and turn golden brown.
12 -
Turn the patties over carefully so the jalapeño-onion topping now sits on top.
13 -
Lay a slice of cheese on four patties and let them cook another 1.5 to 2 minutes until things get melty.
14 -
Pair a plain patty with a cheesed patty to create four stacks of double burgers.
15 -
Slather your sauce on toasted buns and pair with burgers while they're fresh and hot.