In a bowl, combine the mayonnaise, ketchup, mustard, relish, Worcestershire sauce, garlic powder, and black pepper. Mix until smooth and refrigerate until ready to use.
Cook the bacon until crispy. Drain and chop into bite-sized pieces.
Preheat the griddle to 425-450°F. Divide the beef into 8 portions, smash thin, and season with salt, pepper, and garlic powder. Cook 2-3 minutes until a deep crust develops, flip, top with American cheese, and melt completely.
On a clean section of the griddle, pile together the iceberg lettuce, diced tomato, white onion, crispy bacon, crispy fried onions, and half the burger sauce. Place the cheeseburgers on top.
Using two spatulas, chop and fold everything together until evenly combined into a flavorful chopped cheeseburger mixture.
Slice the King's Hawaiian rolls in half. Mix melted butter with garlic powder, brush onto the cut sides, and toast on the griddle until golden brown.
Spread additional burger sauce on the toasted rolls. Pile the chopped mixture onto the bottom buns, top with pickles if desired, add top buns, slice into individual sliders, and serve immediately.