Step 1: Prepare your ingredients. Divide your ground beef into 2-ounce (about 55-60g) balls. Do not pack them tightly – keep them loosely formed. Season generously with salt and black pepper on all sides. Have your cheese slices ready, your buns buttered, and all your desired toppings within arm's reach.
Step 2: Heat your cooking surface. Place a heavy-bottomed cast iron skillet or griddle over high heat for at least 5-7 minutes. You want it smoking hot. Do not add oil at this stage; the beef fat will provide all the lubrication needed.
Step 3: Toast the buns. While the pan is heating, lightly butter the cut sides of your potato buns. Once the pan is scorching hot, quickly place the buns cut-side down onto the hot surface. Toast for 30-60 seconds, or until golden brown. Remove immediately and set aside.
Step 4: Smash the patties. Place 1-2 beef balls onto the very hot skillet, ensuring not to overcrowd the pan. Immediately place a piece of parchment paper over each beef ball, then use a sturdy, flat metal spatula (or another heavy pot/pan) to firmly press down on each ball, smashing it into a very thin patty, about 1/4 inch thick. Press hard for 10-15 seconds to maximize contact with the pan and create that incredible crust. Discard the parchment paper.
Step 5: Cook the first side. Let the patties cook undisturbed for 1.5-2 minutes. You'll see the edges start to crisp up and brown, and a beautiful crust will form. Resist the urge to move them!
Step 6: Flip and cheese. Using your spatula, carefully scrape underneath each patty, making sure to get all the crispy bits from the bottom. Flip the patties. Immediately place a slice of American cheese on top of each patty.
Step 7: Finish cooking. Cook for another 30-60 seconds, or until the cheese is perfectly melted and gooey, and the patty is cooked through to your liking (remember, they cook very quickly!). If making a double smash burger, stack one cheesy patty on top of another.
Step 8: Assemble and serve. Transfer the cooked patties to your toasted buns. Add your favorite toppings – pickles, onions, lettuce, tomato, and sauce. Serve immediately and enjoy the crispy, juicy goodness!