One of the things I have made the most on my Blackstone is smash burgers in the close to a year that I have owned the grill. This post will detail the process and outcomes. A little research that I completed resulted in the method that I follow.
The beauty of the Blackstone is to cook multiple items at the same time. As an onion lover one my favorite things is to grill onions to go on top of the burgers. At the same time I am cooking the burgers and onions and sometimes mushrooms, I also like the ability to cook the buns that I am using. This adds a nice touch and addition crunch to the Smashburger. Onions are sliced and dropped on the hot Blackstone with a little oil. I will typically season with salt and pepper and garlic powder. They will take about the same amount of time as the burgers. My Blackstone has 4 burners, for the meal I typically light three, do the onions on the left, burgers in the second zone and the buns on the third zone. Heat can be controlled in all three zones and I personally use a heat gun to ensure they are at the proper temp. About 350 is good for the onions and the buns, I typically go higher on the burgers about 500.
While researching the process of the smash burger, I saw people recommending specific gadgets to smash the burgers. I saw that someone recommended that simply using a folded over piece of wax paper and a decent spatchula will get the job done. That has become the method that I use and it works well. I portion the meat, and roll into a lightly compacted ball. I then take a slice of butter and place it under each ball on the grill. I grill long enough to get a crust on the bottom of the ball and then smash down each burger and cook to get a crust of the smashed portion.