Prep the rolls: If your rolls are not seeded, lightly brush the tops with melted butter and sprinkle sesame seeds over them. Set aside.
Shape the beef: Divide ground beef into two large, even rectangles. Press each into the size of one set of 6 connected rolls, about ½ inch thick. Season both sides with salt and pepper.
Cook the patties: Heat a large skillet or griddle over medium-high. Cook each beef rectangle for 4–5 minutes per side until browned and cooked through. Remove and let rest for 5 minutes.
Assemble base layer: Slice the rolls in half horizontally, keeping each set of 6 intact. Spread burger sauce generously on the bottom half. Sprinkle with onions, then top with a layer of pickles.
Add beef and cheese: Place the cooked beef patty on top of the pickles, then layer 6 slices of American cheese. Add shredded lettuce evenly over the cheese.
Middle bun layer: Place the top halves of the rolls (that you sliced earlier) on top of the lettuce. Spread more burger sauce, sprinkle more onions, add another layer of pickles.
Second beef layer: Place the second cooked beef patty on top, followed by the remaining cheese slices. Finish with shredded lettuce.
Crown the burgers: Add the final top half of the rolls. Gently press down to secure the layers.
Slice and serve: Use a sharp knife to cut into 12 sliders. Serve immediately while warm and gooey.