Ultra-Smashed Double Cheeseburger

1. 1
   Split the buns and coat the cut sides with softened **butter**.
2. 2
   Toast the buns cut-side down in a dry skillet over **medium heat** for **2 minutes** until golden, then set aside.⏱ 2 min
3. 3
   Divide the cold beef into four **2-ounce loose rounds**, handling the meat as gently as possible.
4. 4
   Heat a **12-inch cast-iron skillet** over **high heat** until lightly smoking, about **5 minutes**.⏱ 5 min
5. 5
   Place two cold beef balls into the dry skillet, spaced well apart.
6. 6
   Press each ball flat instantly with a **heavy, stiff metal spatula** until **wafer-thin** with jagged edges.
7. 7
   Season the tops heavily with **kosher salt** and black pepper.
8. 8
   Cook undisturbed for **90 seconds** until the edges are deep brown, lacy, and caramelized.⏱ 2 min
9. 9
   Scrape firmly under each patty using a **sharp-edged spatula** to lift the crust without tearing it.
10. 10
    Flip the patties, top each with a slice of **American cheese**, and cook for **30 seconds**.⏱ 30 sec
11. 11
    Stack the two cheesy patties together and transfer them straight to the toasted bottom bun.
12. 12
    Top with pickle slices, spread with mayonnaise and ketchup, cap with the top bun, and serve immediately.
13. 13
    Shave the onion into paper-thin slices using a **mandoline slicer**, then fluff the strands loosely with your fingers.
14. 14
    Gently shape the cold ground beef into two **4-ounce round pucks**.
15. 15
    Heat a heavy **12-inch cast-iron skillet** over **medium-high heat** until hot, about **4 minutes**.⏱ 4 min
16. 16
    Place the beef pucks onto the dry pan and top each immediately with a **generous handful of shaved onions**.
17. 17
    Smash down firmly with a **stiff metal spatula** directly into the onions until flattened to 1/2-inch thickness.
18. 18
    Season the smashed onion tops generously with **kosher salt** and black pepper.
19. 19
    Sear undisturbed for **3 minutes** until the bottom meat develops a dark brown crust.⏱ 3 min
20. 20
    Slip a spatula underneath and flip cleanly so the **onions are directly on the pan surface**.
21. 21
    Top each beef patty with a slice of **American cheese**.
22. 22
    Place the bottom bun over the cheese, then set the top bun over the bottom bun to steam in the rising beef vapor.
23. 23
    Cook for **3 minutes** until the onions underneath are soft, browned, and caramelized in the rendered fat.⏱ 3 min
24. 24
    Invert the top bun, lift the entire patty and onions with your spatula, place on the bottom bun, and finish with mustard and pickles.