Two smash patties are stacked with melty cheese and finished with a tangy, creamy Burger Sauce. These Loaded Double-Stack Smash Burgers work well with a variety of cooking methods, including flat top grill, cast iron skillet or griddle.

Approximate nutrition information per serving (using 85% lean ground beef; includes Burger Sauce): 840 calories; 57 g fat; 24 g saturated fat; 173 mg cholesterol; 1064 mg sodium; 33 g carbohydrate; 2 g fiber; 6.4 g sugar; 48 g protein
Combine Burger Sauce ingredients and set aside.
Melt butter a large skillet over medium heat. Sauté onions in melted butter, adding water as needed, until caramelized, 20–30 minutes. Remove onions and toast buns in the same skillet. Remove buns from skillet.
Heat the skillet over high heat. Divide ground beef into 8 balls. Working in batches as needed, arrange beef balls in skillet, smashing with a burger press or spatula lined with parchment paper until very thin, about ¼ inch thick. Season tops with salt and pepper and cook until edges begin to crisp, 1½–2 minutes. Flip burgers, then season other side with salt and pepper. Add cheese and cook until melted and burgers are cooked through, about 1 minute more.
To build burgers, layer each bottom bun with Burger Sauce, lettuce, 2 burger patties, onions and pickles. Spoon more Burger Sauce onto top bun and enjoy!