Bone Marrow Wagyu Smash Burger with Caramelized Shallots Step-by-step instructions

Before you start

Before cooking, heat the oven to 450°F. Remove the Wagyu beef from the refrigerator and let it sit at room temperature for no more than 30 minutes. Slice the shallots and set aside.

Gather all ingredients and equipment: cast-iron skillet, spatula, small saucepan, and tongs. Roast the marrow bones first, as they take the longest.

While they roast, caramelize the shallots and form the beef balls. Have the cheese slices ready to go.

Instructions

Roast and Prep

1. 1Roast the Marrow Bones
   Heat the oven to 450°F (230°C). Place the split marrow bones on a small baking sheet and sprinkle with the flaky sea salt. Roast for 15–20 minutes, until the marrow is soft and bubbling. Set aside to cool slightly.
   Look for The marrow should look glossy and slightly puffed, with a rich, beefy aroma.
   Tip If the bones wobble, rest them on a bed of coarse salt to keep them steady.
2. 2Caramelize the Shallots
   While the marrow roasts, melt the butter in a small skillet over medium heat. Add the sliced shallots and cook, stirring occasionally, until golden and soft, about 8–10 minutes. Remove from heat and set aside.
   Look for The shallots turn translucent, then deepen to a golden brown with a sweet, nutty smell.
   Tip Keep the heat moderate so the shallots caramelize without burning.
3. 3Form the Wagyu Patties
   Divide the Wagyu beef into two equal portions and gently shape each into a loose ball. Do not overwork the meat; handle as little as possible to keep it tender.
   Look for The balls should be loosely packed and about 4 ounces each.
   Tip Chilling the balls for 10 minutes helps them hold together during smashing.

The marrow should be soft and bubbling, with a rich, beefy aroma. The shallots should be golden and sweet. The beef balls should be loosely packed and chilled. The oven should be at 450°F, and the skillet should be heating up.

Smash and Melt

4. 4Smash the Patties
   Heat a dry cast-iron skillet or griddle over high heat until smoking, about 480°F (250°C). Place one beef ball in the skillet and immediately smash it flat with a spatula. Cook for 75 seconds without moving, until the edges are lacy and browned. Flip and cook for another 75 seconds.
   Look for The patty should have a dark, crispy crust with frilly edges.
   Safe temperature 160°F (71°C) internal temperature (ground meat)
   Tip Use a firm, even press to get maximum crust.
5. 5Add Cheese and Marrow Butter
   Place two slices of cheddar on each patty during the last minute of cooking. Spoon about 1 1/2 tablespoons of the roasted marrow over each patty, letting it melt into the cheese.
   Look for The cheese melts and the marrow sizzles as it hits the hot patty.
   Tip Use the marrow from the roasted bones; if it has cooled, reheat it gently.
6. 6Toast the Buns
   Split the brioche buns and toast them cut-side down in the same skillet until golden, about 30 seconds. Set aside.
   Look for The buns turn golden brown with a light crunch.
   Tip Toasting in the beef fat adds extra flavor.

The patties should have a dark, crispy crust with lacy edges. The cheese should be melted and the marrow bubbling over the top. The buns should be toasted golden brown. The kitchen should smell intensely of beef and butter.

Assemble and Serve

7. 7Assemble the Burgers
   Place each patty on a toasted bun bottom. Top with the caramelized shallots, then add the bun tops. Slice in half if desired, and serve immediately while the marrow is molten.
   Look for The cross-section shows the juicy patty, melted cheese, and glistening marrow.
   Tip Use a serrated knife for a clean cut without squishing the burger.

The burgers should be assembled with the patties on the bottom bun, topped with caramelized shallots, and covered with the top bun. When sliced, the cross-section should show the juicy patty, melted cheese, and glistening marrow. Serve immediately.

Common mistakes

Overworking the beef can make the patties tough. Handle the meat gently and shape it into loose balls. Not getting the skillet hot enough will result in a pale, steamed patty instead of a crispy one.

Wait until the skillet is smoking before adding the beef. Smashing too hard can push out all the juices; use a firm but gentle press. Also, avoid moving the patty while it cooks—let it develop a crust undisturbed.

How to tell it’s done

The burger is done when the patty reaches an internal temperature of 160°F (71°C) for well-done, but for a smash burger, the thin patty cooks quickly and the crust is the main indicator. The cheese should be fully melted and the marrow bubbling.

The buns should be toasted golden brown. The shallots should be soft and caramelized, with a deep golden color. The final burger should be juicy, with the marrow and cheese flowing from the center.

• Ground meat: 160°F (71°C) in the thickest part
• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest