Fire up your blackstone to high - get it hot.
Find that thin blade knife.. Halve your onion and slice it as thin as you can. You want a pile of strands.
Use your preference for burger slices - I went with 3-4oz patties to fill the bun. Roll it up into a ball.
Throw the butter on the Blackstone, distribute throughout your cooking surface
Slap those meat balls on the griddle, sprinkle some seasonings on it and put a quarter of the onions on each ball.
Use your flipper and smash the burger/onion pile so the patty is pretty darn thin.
Let it cook for a minute or two - waiting for the gray/brown to get to the top of the patty edge. You get one shot at this - don't worry about burning it.
Flip it, and let the onions and beef work on cooking this side. You should see a beautiful crispy char staring at you. Cover it with another dust of seasoning, a Kraft square, and let that other side cook for a minute or so.
Put that bottom bun on there with the top bun right on top of it. Let that meaty, oniony steam attach itself to the buns. When you're ready, weak hand your top bun, strong hand your flipper and marry the two. Fancify it with a pickle or two, or 5 - You got yourself the Oklahoma Onion!