Loaded Lamb Smash Burger Recipe

If you’re looking for the best smash burgers recipe that’s juicy, flavor-packed, and a little bit gourmet — you’re in the right place. I fell in love with smash burgers many years ago when I tried my first one in Argentina. Smash burgers became a national craze a bunch of years ago and burger joints started popping up everywhere back home in Buenos Aires. During one of my trips there I tried the best smash burger I’ve ever had from a little chain burger joint called Burger Couple, opened by a young couple in Argentina. Ever since that day I fell in love with the technique and started testing different combinations at home. This one is by far one of the best ones I’ve come up with and I’m super excited to share it with you!

This loaded lamb smash burger has it all: buttery sautéed mushrooms, melty brie cheese, and a rich caramelized onion crema that elevates this smash burger to a must-have.

This is hands down one of the best homemade burgers you’ll ever eat. Let’s get into it!

Why You’ll Love This Smash Burger Recipe

• Crispy edges, juicy center: The smash technique gives you the perfect sear.
• Gourmet flavors: Brie, lamb, and a rich crema elevate this far beyond your average burger using ingredients you already have at home.
• Quick to make: Ready in under 30 minutes.

It’s also customizable! You can swap in different cheeses, greens, or even sauces if you like.

Loaded Smash Burger Ingredients

For the Lamb Smash Burgers:

• 450g ground lamb (medium ground beef works too), portioned into golf ball-sized balls
• 5 cremini mushrooms, thinly sliced
• 1 sprig fresh rosemary (about ½ tsp finely chopped)
• 2–3 sprigs fresh thyme (about 1 tsp fresh thyme leaves)
• Butter lettuce (or leaf lettuce)
• Brie cheese, sliced
• Unsalted butter
• Brioche burger buns
• Canola or vegetable oil (for sauteing)
• Salt and pepper

For the Caramelized Onion Crema:

• ¼ cup mayonnaise
• ¼ cup sour cream
• 1 small onion, thinly sliced
• 2 garlic cloves
• 1 tsp Worcestershire sauce
• 1 tsp balsamic vinegar
• Pinch of paprika (optional)
• Salt and pepper

How to Make the Best Homemade Smash Burgers

1. Make the Caramelized Onion Crema

• Thinly slice and caramelize a small onion slowly in butter until deep golden brown (about 15–20 minutes).
• Let it cool slightly.
• In a bowl, mix the mayonnaise and sour cream.
• Finely chop or lightly blend the caramelized onion and stir it into the mixture.
• Add Worcestershire sauce, balsamic vinegar, paprika (optional), and season with salt and pepper.
• Chill until ready to use.

2. Portion and Chill the Lamb

• Gently roll the ground lamb into 5 equal golf ball-sized portions.
• Set them on a plate or tray and refrigerate while you prepare the toppings.

3. Sauté the Mushrooms

• Heat a splash of oil and a small knob of butter in a pan over high heat.
• Add sliced mushrooms and let them sear undisturbed for about 30 seconds.
• Stir occasionally until cooked through.
• Add the finely chopped rosemary and thyme toward the end of cooking.
• Season with salt and pepper, then set aside.

4. Smash and Cook the Lamb Patties

• Heat a cast iron or heavy-bottomed pan over medium heat with a bit of oil.
• Place a lamb ball in the pan, top with parchment paper, and firmly smash with a spatula to about ½ inch thickness.
• Hold pressure for about 30 seconds for a good crust.
• Remove parchment, season with salt and pepper, flip, and cook the other side.
• Immediately top each patty with slices of brie.
• Repeat to create double-stacked patties.
• Transfer the burger stacks to a 350°F (175°C) oven for a few minutes to fully melt the cheese or simply splash some water into the pan you seared your patties, throw a lid on for a minute until the cheese melts.

5. Toast the Buns

• Melt a little butter in a pan over medium-low heat.
• Toast the brioche buns face-down until golden brown and buttery.

6. Assemble the Loaded Smash Burger

• Spread caramelized onion crema generously on the bottom bun.
• Add a few leaves of butter lettuce.
• Stack on the double brie-lamb patties.
• Pile on the rosemary-thyme mushrooms.
• Spread more caramelized onion crema on the top bun and crown the burger.

Prepare for serious messy, juicy, rich deliciousness!

Serving Suggestions

This burger pairs perfectly with:

• Rosemary garlic fries
• Beer battered onion rings
• A crisp arugula salad
• A cold beer or a bold red wine like Syrah

Print Recipe

Loaded Smash Burger with Lamb, Brie & Caramelized Onion Crema

Prep Time25 minutes mins

Cook Time20 minutes mins

Servings: 2 double-stacked burgers

Ingredients

Burgers:

• 450 g ground lamb portioned into 5 golf ball-sized balls
• Salt and pepper to taste
• Brie cheese sliced
• Butter lettuce leaves
• Brioche burger buns
• Unsalted butter for toasting buns
• Canola or vegetable oil for cooking

Sautéed Mushrooms:

• 5 cremini mushrooms thinly sliced
• 1 sprig fresh rosemary chopped
• 1 sprig fresh thyme chopped
• 3 leaves fresh sage chopped
• 1 tbsp unsalted butter
• Splash of olive oil
• Salt and pepper to taste

Caramelized Onion Crema:

• ¼ cup mayonnaise
• ¼ cup sour cream
• 1 small onion thinly sliced
• 2 garlic cloves minced
• 1 tsp Worcestershire sauce
• 1 tsp balsamic vinegar
• 2 tsp of sugar
• Pinch of paprika optional
• Salt and pepper

Instructions

• Portion lamb into 5 balls. Chill until ready to cook.
• Make caramelized onion crema:
• Cook onions slowly in butter over medium-low heat. Season with a pinch of salt. Once golden, add minced garlic, sugar and sautee for about a minute. Let cool. Blend with sour cream, mayo, salt, and pepper until smooth.
• Sauté mushrooms:
• In a hot pan, melt butter and a little oil. Add mushrooms. Let them sear for 30 seconds, then stir. Add rosemary, thyme and sage. Cook until golden. Season with salt and pepper.
• Cook smash burgers:
• Heat a pan over medium. Add oil. Smash each lamb ball flat using parchment paper and a spatula. Season. Cook 30 seconds, flip, season again. Top each patty with brie.
• Stack burgers:
• Stack two patties together with brie in between. Keep warm in a 350°F oven to melt the cheese fully.
• Toast buns:
• Butter buns and toast face-down in a pan until golden.
• Assemble:
• Spread caramelized onion crema on the bottom bun. Add lettuce, the double-patty stack, sautéed mushrooms, more crema on the top bun, and close it up. Enjoy!

Notes

• Smash burgers cook quickly — keep an eye on them!
• Lamb adds rich flavor but you can substitute ground beef if preferred.
• The caramelized onion crema also makes a great dip for fries!

Final Thoughts on This Loaded Smash Burger

This isn’t your everyday burger — it’s a full-on experience.
The rich lamb, gooey brie, earthy mushrooms, and creamy caramelized onion crema come together to create one of the best homemade burgers you’ll ever sink your teeth into.

This smash burger recipe is perfect to start you off on your smash burger making journey. Once you have the technique down, the possibilities and combinations are endless. Try different toppings, sauces, cheeses and buns and make one your own. 

Let us know what you think down in the comments!