Dividing the beef into 8 pieces, prepare the meat by loosely rolling into 8 balls. You want to keep the meat loose because it smashes better! Keep in the refrigerator until ready to smash and grill. You can separate on a plate with parchment paper so they don’t stick.
Preheat the griddle over medium high heat (approximately 400 degrees F). If working with a large griddle, you can prepare all 8 patties at once (4 burgers). If a small griddle, you’ll want to work in batches (2), etc.
Prepare the buns: Butter the buns (about 1 Tbsp butter) and place them on the griddle for 2 minutes to toast. Set aside while you start cooking the burgers.
Add the remaining 1 Tbsp of butter to the grill and allow it to melt. With a spatula, move it around, and then place the 4 balls of beef on the griddle or grill.
Next, add a piece on parchment paper one on each ball of beef, and then firmly press down with the burger press to smash the beef into a thin patty. TIP: You can use either a burger press or a large spatula. After pressing, toss the parchment paper.
Season with the patties with salt and pepper.
Cook the patties until the juices in the beef start to show and the color starts to change, about 2 minutes. With a spatula, flip the patty, getting all the juices with it.
ONLY SMASH THE BURGER ONCE: Once you flip the burger, cook for additional 1 minute. and place a piece of cheese on 2 of the patties to melt. Once the cheese is melted, top each 2 with the plain patty, to make a double patty (with cheese in the center).
If you haven’t smashed all the patties (and you are working in batches), then move those patties to a separate platter and continue this process until all the patties have been prepared.
ASSEMBLE THE BURGER:
On the bottom of a bun, place the lettuce, tomato slice, red onions, and pickles on the bottom bun. Add the double patty on top and top, drizzle with mustard and ketchup, and place the top bun on top.