Add the mayonnaise, ketchup, yellow mustard, finely chopped dill pickles, pickle juice, sugar, paprika, garlic powder, onion powder, salt, and black pepper to a small mixing bowl.
Mix thoroughly with a whisk or spoon until the mixture becomes smooth, creamy, and glossy.
Taste and adjust the flavors to your preference: add more pickle juice for extra tang, or a bit more ketchup if you prefer a sweeter spread.
Cover and chill the mixture in the refrigerator for 20 to 30 minutes to achieve authentic smash-joint flavor.
Spread generously on both sides of a toasted bun, then add double smashed beef patties, American cheese, shredded lettuce, and pickles.