Heat Blackstone griddle to medium-high heat.
Prepare everything ahead so when you start cooking you are ready. This includes buns, burgers, onions and cheese. A food prep cart is helpful. Pre slice burger buns. Can add mayonnaise if desired. Tip: If you are new to the Blackstone, you can toast your burger buns first if you don’t want to do too many things at once.
Thinly slice onions (shaved, mandolin or thin slice).
Roll 80/20 burger patties into balls. Don’t over pack your smash burger balls. Each ball should be approximately ⅓ pound (¼ cup overflowing). Do not make them too large.
Place slices of Kraft American cheese (or other cheese of choice) in easy to grab stack on a plate and set to the side.
If using onions in your smash burgers, place onions down in separate piles (one for each burger).
Place smash burgers on each onion pile on Blackstone griddle (directly on griddle if no onions).
Sprinkle each burger with hamburger seasoning of choice. Smash each burger down and hold for about 5-10 seconds (you can use a piece of parchment paper in top of each burger to make smashing easier).
You can use a Blackstone spatula to smash or a burger smasher.
Once you smash burgers, add extra hamburger seasoning to burgers if desired. Toast bread in separate area (if you don’t pre-toast burger buns). About 30-60 seconds on each side.
When burgers start to sweat and turn brown at bottom, flip them. Optional: You can add a drizzle of mustard before flipping for some extra tang and crust on the burger.
Add Kraft American cheese (or cheese of choice) to top of Blackstone smash burgers.
Optional: squirt a little water on Blackstone around (not on) the burgers to help steam cheese.
Once burgers are fully cooked, transfer to bun and add any desired toppings such as lettuce, tomato, onion, ketchup or mustard and enjoy!