Bone Marrow Wagyu Smash Burger with Caramelized Shallots Tips, FAQ & printable recipe

Tips for success

For the best crust, use a heavy cast-iron skillet or griddle and preheat it for at least 10 minutes on high heat. The surface should be smoking before you add the beef.

Use a thin, sharp spatula to scrape the patty off the pan when flipping to preserve the crust. If you don't have a smasher, use the back of a spatula or a small saucepan.

When roasting the marrow bones, place them on a bed of coarse salt to keep them stable.

If the marrow starts to melt out of the bones, it's fine—just collect it and use it for basting. The marrow can also be scooped out and spread on the bun for extra richness.

Variations

• Truffle Burger: Add a drizzle of truffle oil or a few shavings of fresh truffle over the marrow-basted patty for an extra-luxurious finish. The earthy aroma pairs beautifully with the beef and shallots.
• Spicy Kick: Add a few slices of pickled jalapeños or a drizzle of hot sauce to the burger for a tangy, spicy contrast. The heat cuts through the richness and adds brightness.
• Blue Cheese Version: Swap the aged white cheddar for crumbled blue cheese. Its pungent, salty flavor complements the beef and marrow, and it melts into a creamy, tangy sauce.
• Smoky Twist: Add a slice of smoked bacon or a sprinkle of smoked paprika to the patty before cooking. The smokiness adds another layer of depth that pairs well with the charred crust.

Storage and make-ahead

Fridge

Store leftover burgers in an airtight container in the refrigerator for up to 2 days. Reheat gently in a skillet to avoid drying out.

Freezer

Freeze cooked burgers in a single layer on a baking sheet, then transfer to a freezer bag for up to 1 month. Reheat in a 350°F oven until hot.

Reheat

Reheat frozen or refrigerated burgers in a skillet over medium heat, covered, until warmed through. Add a splash of water or broth to keep them moist.

Leftover burgers can be stored in an airtight container in the refrigerator for up to 2 days.

Reheat in a skillet over medium heat to restore some crispness, but note that the marrow and cheese will not be as molten as when fresh. The marrow bones can be stored separately and reheated gently.

The caramelized shallots can be made up to 2 days ahead and stored in the refrigerator.

The marrow bones can be roasted a day ahead and kept covered in the refrigerator; reheat them gently before using. The Wagyu beef balls can be formed and refrigerated for up to 24 hours before cooking.

Serving ideas

Serve the burgers immediately after assembling, while the marrow is still molten and the cheese is gooey. A sharp knife will help cut through the crispy crust and soft bun. Pair with a robust red wine, such as a Zinfandel or Syrah, to complement the richness.

For a complete meal, serve alongside crispy fries or a simple green salad with a tangy vinaigrette to cut through the fat. The burger is rich, so portion sizes are generous—one per person is plenty. Enjoy it as a special treat for a date night or celebration.

Frequently asked questions

Recipe card

Bone Marrow Wagyu Smash Burger with Caramelized Shallots

Prep 20 minCook 20 minRest 5 minTotal 45 minServes 2

Ingredients

• 2 split beef femur marrow bones
• 1 tsp flaky sea salt
• 8 oz A5 Wagyu beef trim
• 4 slices aged white cheddar
• 2 brioche burger buns
• 2 shallots, thinly sliced
• 1 tbsp unsalted butter

Instructions

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. Split the brioche buns and toast them cut-side down in the same skillet until golden, about 30 seconds. Set aside.
7. 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.

Contains: gluten, milk, eggs

Estimated nutrition per serving

Calories

950

Protein

45 g

Carbohydrates

40 g

Fat

65 g

Automatic estimate from the ingredient list, not laboratory-verified.