Make the ShackSauce by combining mayonnaise, ketchup, mustard, pickle brine, garlic powder, and onion powder in a small bowl. Mix well, cover, and refrigerate until ready to use.

Divide the ground beef into 4 equal portions of 4 ounces each. Gently roll each portion into a loose ball without overworking the meat. Keep refrigerated until ready to cook.

Heat a cast-iron skillet or griddle over high heat until smoking hot. This high temperature is crucial for achieving the signature crispy crust.

Butter the inside of each hamburger bun and toast them cut-side down on the hot griddle until golden brown, about 1-2 minutes. Remove and set aside.

Place a beef ball on the hot griddle and immediately smash it flat using a heavy spatula or burger press. Press firmly for 10 seconds to create maximum surface contact.

Season the patty generously with salt and black pepper. Let it cook undisturbed for 2-3 minutes until a dark brown crust forms.

Flip the patty carefully, season the cooked side, and immediately place a slice of American cheese on top. Cook for another 2 minutes until the cheese melts.

Repeat the smashing and cooking process with remaining beef balls, working in batches if necessary.

Assemble the burgers by spreading ShackSauce on both the top and bottom buns. Place lettuce on the bottom bun, followed by the cheesy patty, tomato slice, and top bun.

Serve immediately while hot and enjoy your homemade Shake Shack burgers with crispy fries or onion rings on the side.