Portion Beef Patties: Divide ground beef into 8 equal portions (about 3 oz each). Gently roll each portion into loose balls. Cover with plastic wrap and chill in the fridge until ready to cook. Keeping the meat cold ensures a better sear and texture.
Prep Toppings and Buns: Discard any wilted lettuce leaves and shred the fresh ones finely. Slice tomatoes, onions, and pickles into even pieces for layering. Butter the cut sides of the buns and toast them on a griddle or skillet over medium heat until golden brown. Set aside.
Cook the Patties: Preheat a griddle or large skillet over medium-high heat until hot. Place 2-4 beef balls on the griddle, ensuring enough space to smash them. Cover each beef ball with parchment paper and smash firmly with a spatula until thin. Remove the parchment paper and discard. Season the patties with salt, pepper, garlic powder, and spread 1/2 teaspoon burger sauce over each patty. Cook for 2 minutes or until the edges caramelize and juices begin to surface.
Flip and Stack: Using a spatula at a 45˚ angle, scrape under the patty to preserve the caramelized crust, then flip. Cook the other side for 1 minute. Add a slice of cheese to half the patties, then stack a second patty on top of the cheese-covered one. Transfer cooked patties to a platter and keep warm.
Assemble Burgers: Spread burger sauce on the bottom bun. Layer with 3 pickle slices, shredded lettuce, 2 tomato slices, and thin-sliced onion. Place the double patty stack on top of the toppings. Cover with the toasted top bun.
Serve: Serve immediately with French fries, onion rings, or your favorite sides. Enjoy!