Cheesy Smash Burgers With Caramelized Onions and House Sauce

Quick Recipe Version (TL;DR)

• Yield: 4 double smash burgers (4 servings)
• Prep Time: 20 minutes
• Cook Time: 25 minutes
• Total Time: 45 minutes

Quick Ingredients

• 1 1/2 lb (680 g) 80/20 ground beef, cold
• 2 large yellow onions, thinly sliced
• 8 slices American or mild cheddar cheese
• 4 soft burger buns (brioche or potato)
• 3 1/2 tbsp unsalted butter (buns + onions)
• 1 tbsp olive oil + 1 tbsp neutral oil
• 1/2 tsp sugar, 1 3/4 tsp kosher salt, 3/4 tsp black pepper
• 1/2 cup mayonnaise, 2 tbsp ketchup, 1 tbsp yellow mustard
• 2 tbsp finely chopped dill pickles or relish
• 1 tsp apple cider vinegar, 1/4 tsp garlic powder, 1/4 tsp smoked paprika
• Dill pickle slices, optional lettuce and tomato for serving

Do This

• 1. Stir together mayonnaise, ketchup, mustard, chopped pickles, vinegar, garlic powder, smoked paprika, salt and pepper; chill.
• 2. Slowly caramelize sliced onions in butter, olive oil, salt and sugar over medium-low heat until deep golden, 20 to 25 minutes.
• 3. Divide cold beef into 8 loose balls (about 3 oz / 85 g each); keep chilled. Split buns and butter the cut sides.
• 4. Heat a cast-iron skillet or griddle over medium-high with a light film of oil. Add beef balls, press very flat with a sturdy spatula over parchment, and season.
• 5. Sear 1 1/2 to 2 minutes until edges are crispy and browned. Flip, immediately top with cheese, and cook 30 to 60 seconds more.
• 6. Toast buns cut-side down in butter until golden. Spread sauce on buns, stack 2 patties per burger, top with caramelized onions, pickles, and optional lettuce/tomato.

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Why You’ll Love This Recipe

• Ultra-thin, crispy-edged patties with gooey melted cheese in every bite.
• A tangy, creamy house sauce that tastes like your favorite burger joint, but better.
• Deeply caramelized onions add sweetness and richness without being fussy.
• All done with simple ingredients and basic pans you likely already own.

Grocery List

• Produce: Yellow onions, lettuce (optional), tomato (optional), fresh herbs for garnish (optional).
• Dairy: American or mild cheddar cheese slices, unsalted butter, mayonnaise.
• Pantry: Ground beef (80/20), burger buns, ketchup, yellow mustard, dill pickles or relish, olive oil, neutral oil, apple cider vinegar, sugar, kosher salt, black pepper, garlic powder, smoked paprika, cayenne or hot sauce (optional).

Full Ingredients

For the Smash Burgers

• 1 1/2 lb (680 g) 80/20 ground beef, very cold
• 1 1/4 tsp kosher salt, divided (plus more to taste)
• 3/4 tsp freshly ground black pepper, divided (plus more to taste)
• 8 slices American cheese or mild cheddar (about 6 oz / 170 g)
• 4 soft burger buns (brioche or potato buns work well)
• 2 tbsp unsalted butter, softened (for toasting buns)
• 1 tbsp neutral oil (canola, vegetable, or avocado) for the griddle
• 8–12 dill pickle slices
• 4 leaves crisp lettuce (romaine or iceberg), optional
• 4 slices ripe tomato, optional

For the Caramelized Onions

• 2 large yellow onions (about 1 lb / 450 g), peeled and thinly sliced pole-to-pole
• 1 1/2 tbsp unsalted butter
• 1 tbsp olive oil
• 1/2 tsp kosher salt
• 1/2 tsp sugar (optional, helps browning)
• 2–3 tbsp water, as needed, to deglaze the pan

For the Tangy House Sauce

• 1/2 cup mayonnaise
• 2 tbsp ketchup
• 1 tbsp yellow mustard
• 2 tbsp finely chopped dill pickles or dill relish
• 1 tsp apple cider vinegar
• 1/4 tsp garlic powder
• 1/4 tsp smoked paprika
• Pinch cayenne pepper or a few dashes hot sauce, optional
• Freshly ground black pepper, to taste

Step-by-Step Instructions

Step 1: Make the tangy house sauce

In a small bowl, mix together the mayonnaise, ketchup, yellow mustard, finely chopped dill pickles (or relish), apple cider vinegar, garlic powder, smoked paprika, and cayenne or hot sauce (if using). Season with a small pinch of kosher salt and a few grinds of black pepper.

Taste and adjust: add a little more vinegar for tang, ketchup for sweetness, or hot sauce for heat as you like. Cover and refrigerate while you prepare the onions and burgers. The flavors get even better as it rests.

Step 2: Caramelize the onions

Heat a large skillet over medium heat. Add the butter and olive oil. Once the butter is melted and foamy, add the sliced onions and sprinkle with the kosher salt and sugar (if using). Toss to coat the onions evenly in the fat.

Cook, stirring every few minutes, until the onions gradually soften and turn deep golden brown, 20 to 25 minutes. If they start to brown too quickly or stick, lower the heat to medium-low and add a tablespoon of water at a time to deglaze the pan, scraping up the browned bits.

When the onions are soft, jammy, and a rich caramel color, taste and adjust seasoning with a pinch more salt if needed. Turn off the heat and set aside. You can keep them warm over very low heat or rewarm briefly before serving.

Step 3: Prep the beef and buns

While the onions cook, prepare the burger patties. Divide the cold ground beef into 8 equal portions, about 3 oz (85 g) each. Very gently roll each portion into a loose ball; do not compact the meat too much, or the patties will be dense. Place the beef balls on a plate or tray and keep them in the refrigerator until just before cooking so they stay cold.

Split the burger buns and spread the cut sides with the softened butter. Set them aside near the stove so you can toast them while the patties cook.

Have your cheese slices unwrapped and ready, along with the caramelized onions, pickles, lettuce, tomato, and house sauce. Smash burgers cook fast, so it is helpful to have everything prepped and within reach.

Step 4: Smash and sear the patties

Heat a large cast-iron skillet or flat griddle over medium-high heat until very hot, about 3 to 5 minutes. You want it just barely smoking. If you have an infrared thermometer, aim for around 400–450°F (200–230°C). Lightly coat the surface with the neutral oil.

Working in batches so you do not overcrowd the pan, place 2 to 3 beef balls onto the hot surface, leaving space between them. Immediately lay a small piece of parchment paper over each ball. Using a sturdy, flat metal spatula (or burger press), press down firmly to smash the beef into a very thin patty about 1/4 inch (6 mm) thick. Press hard for 5 to 10 seconds so the meat really makes contact with the pan.

Peel off the parchment and sprinkle each patty lightly with kosher salt and black pepper. Let the patties cook, undisturbed, until the edges are deeply browned, crispy, and lacy and the top looks mostly cooked through, 1 1/2 to 2 minutes.

Step 5: Flip, melt the cheese, and toast the buns

Using your spatula, scrape firmly under each patty to release that flavorful browned crust, then flip. Immediately top each patty with a slice of cheese.

Cook for another 30 to 60 seconds, just until the cheese is fully melted and the patties are cooked through but still juicy. Transfer the patties to a warm plate and repeat with the remaining beef balls, adding a touch more oil if the pan looks dry.

While the last batch of patties cooks, place the buttered buns cut-side down on another skillet or on an open spot on the griddle. Toast over medium heat until the edges are golden brown and the centers are lightly crisp, 1 to 3 minutes. Remove from the heat.

Step 6: Build the cheesy smash burgers

To assemble each burger, spread a generous spoonful of house sauce on the bottom bun. Place two cheesy patties on top, stacking them slightly off-center so you can see the melted cheese and crispy edges.

Spoon a pile of warm caramelized onions over the patties. Add dill pickle slices, and, if you like, a leaf of crisp lettuce and a slice of tomato.

Spread a little more house sauce on the cut side of the top bun, then cap the burger. Serve immediately while everything is hot, cheesy, and the buns are still toasty.

Pro Tips

• Keep the beef cold: Cold meat sears better and releases less fat, giving you juicier burgers with a crispier crust.
• Smash once, then leave it: Only press the patties down at the beginning. After that, do not press again, or you will squeeze out the juices.
• Use a sturdy metal spatula: A thin, stiff spatula helps you scrape up the crust without tearing the patty.
• Do not overcrowd the pan: Cooking in small batches keeps the heat high and prevents steaming, which is key for those browned, lacy edges.
• Balance the sauce: If your sauce tastes too rich, add a little extra vinegar. If it is too sharp, add a touch of ketchup or mayo to mellow it out.

Variations

• Spicy smash burgers: Add extra hot sauce or finely minced jalapeños to the house sauce, and sprinkle the patties with a pinch of cayenne before searing.
• Bacon smash burgers: Cook a few strips of bacon until crisp and layer them on top of the cheese before adding the caramelized onions.
• Onion smash style: Press a small handful of very thinly sliced raw onions into the top of each beef ball before smashing so the onions cook directly into the patty.

Storage & Make-Ahead

Smash burgers are at their absolute best right off the griddle, but you can prep several components ahead.

The house sauce can be made up to 3 days in advance and stored in an airtight container in the refrigerator. The caramelized onions can also be made 2 to 3 days ahead; cool completely, refrigerate in a covered container, and gently rewarm in a skillet over low heat with a splash of water.

If you have leftover cooked patties, cool them quickly, then store in an airtight container in the refrigerator for up to 2 days. Reheat gently in a hot skillet for 1 to 2 minutes per side and add fresh cheese as they warm. Buns are best toasted fresh just before serving.

Nutrition (per serving)

Approximate values for 1 double smash burger with bun, cheese, sauce, caramelized onions, and pickles: about 850 calories, 45 g protein, 55 g fat, 45 g carbohydrates, 3 g fiber, and 1,450 mg sodium. Actual values will vary based on specific ingredients, cheese type, bun size, and how much sauce you use.