First prepare your toppings, including mixing the sauce ingredients together and have the buns and cheese slices at the ready. NOTE: you may also start preparing your optional sides. If making frozen fries, this is the perfect time to get them baking in the oven.
Roll up your ground beef into 8 different balls, placing on a parchment-lined baking sheet and seasoning generously with salt.
Heat a large cast iron skillet or griddle over med-high heat, adding a little drizzle of olive oil. Spray your spatula or burger press with some cooking spray or grease with olive oil. Now you're ready to cook!
Add a ball of beef, then smash immediately with an extra-wide stainless steel spatula (pressing down with a mallet) or burger press. Remove the press, then cook for 1 minute until a crust forms on the bottom. Flip, then season with a bit more salt and add cheese if desired. Cook another 30-60 seconds, then remove from heat and add to a plate. Repeat with remaining balls, except you will only add 2 more cheese slices to 2 more of the burgers.
When burgers are done, add a bit of butter to the pan then add buns. Cook for 30-60 seconds until lightly toasted.
Now assemble your burgers! Add patty with cheese to the bottom, followed by a plain patty. Top with pickle slices, tomato, red onion and lettuce, adding sauce to the top burger bun then placing on burger. Serve with desired side dishes and enjoy!