This recipe comes from the actual guys at Shake Shack! They released the recipe in their book, Shake Shack: Recipes & Stories.
Tip for the side dish: Instead of making my own fries, I baked Ore-Ida frozen crinkle cut fries in the oven and then covered them in melted american cheese. Tasted exactly like the Shake Shack cheese fries.
For our salt & pepper mix:
In a small bowl, mix the kosher salt with the pepper burgers as they cook. Set aside.
For the ShackSauce:
In a small bowl, combine all ingredients and stir to combine. Set aside.
For the ShackBurger:
1. Heat a cast-iron griddle over medium-low heat until warm. Meanwhile, open the hamburger buns and brush the insides with the melted butter. A soft brush is helpful here. Place the buns buttered side down on the griddle and toast until golden brown, 2 to 3 minutes. Transfer buns to a plate. Spoon the sauce onto the top bun. Add a piece of the lettuce and two slices of tomato.
2. Increase the heat to medium and heat the griddle until hot, 2 to 3 minutes.
3. Evenly sprinkle a pinch of the salt & pepper mix on top of each puck of meat.
4. Place the pucks on the griddle, seasoned side down. Using a large, sturdy metal spatula, firmly smash each puck into a 1/3-inch thick round patty. Pressing down on the spatula with another stiff spatula helps flatten the burger quickly. Evenly sprinkle another big pinch of the salt & pepper mix.
5. Cook the burgers, resisting the urge to move them, until the edges beneath are brown and crisp, and juices on the surface are bubbling hot, about 2½ minutes. Slide one of the spatulas beneath the burger to release it from the griddle and scrape up the caramelized browned crust. Use the other spatula to steady the burger and keep it from sliding. Flip the burgers. Put the cheese on top and cook the burgers 1 minute longer for medium. Cook more or less depending on your preference.
6. Transfer the cheeseburgers to the prepared buns and enjoy.