Smash Burger with Caramelized Onions Tips, FAQ & printable recipe

Tips for success

For the best crust, make sure your griddle is absolutely ripping hot before you add the beef. You should see a wisp of smoke. Press the patty firmly and hold for a full 10 seconds to ensure maximum contact with the hot surface. Don't overcrowd the pan—cook in batches if needed to maintain heat.

Caramelizing onions takes time, but the result is worth it. If you're short on time, you can speed up the process by adding a pinch of sugar or a splash of water to help them soften.

However, the slow method yields the deepest flavor. Store any leftover caramelized onions in an airtight container in the fridge for up to a week.

Variations

• Bacon Smash Burger: Add crispy bacon strips on top of the cheese before adding the onions. The smoky, salty flavor pairs beautifully with the sweet caramelized onions and juicy beef.
• Spicy Smash Burger: Mix a pinch of cayenne pepper or chipotle powder into the ground beef before forming the balls. Add sliced jalapeños on top for extra heat.
• Mushroom Smash Burger: Sauté sliced mushrooms with the onions and use them as a topping. The earthy mushrooms complement the beef and cheese wonderfully.
• BBQ Smash Burger: Brush the cooked patties with your favorite barbecue sauce before adding the cheese. Top with crispy fried onions for a crunchy texture.

Storage and make-ahead

Fridge

Store leftover burgers in an airtight container in the refrigerator for up to 3 days. Keep patties and onions separate from buns to prevent sogginess.

Freezer

Cooked patties can be frozen for up to 3 months. Wrap individually in plastic wrap and place in a freezer bag.

Reheat

Reheat patties in a skillet over medium heat for 2-3 minutes per side, or in a 350°F (175°C) oven for 5-7 minutes. Toast buns before serving.

Leftover burgers can be stored in an airtight container in the refrigerator for up to 3 days. Keep the components separate if possible: the patties, onions, and buns individually.

Reheat the patties in a skillet over medium heat until warmed through, about 2-3 minutes per side. Toast the buns again for best texture. The caramelized onions can be reheated in the microwave or on the stovetop.

The caramelized onions can be made up to 3 days ahead and stored in the refrigerator. The beef balls can be formed and kept chilled for up to 24 hours before cooking.

Toasting the buns can be done just before serving, but you can also toast them ahead and reheat in a low oven (300°F/150°C) for a few minutes. Assemble the burgers just before serving to keep everything hot and crisp.

Serving ideas

Serve these smash burgers hot off the griddle, with the cheese still melty and the onions warm. They're perfect on their own, but you can pair them with crispy fries, a simple green salad, or pickles on the side. For a classic diner experience, serve with a cold milkshake or soda.

These burgers are great for casual gatherings—set up a burger bar with toppings like lettuce, tomato, pickles, and condiments, and let everyone build their own.

The caramelized onions are a standout topping, so make sure to have plenty. Enjoy the combination of crispy edges, juicy beef, and sweet onions in every bite.

Frequently asked questions

Recipe card

Smash Burger with Caramelized Onions

Prep 10 minCook 12 minTotal 22 minServes 4

Ingredients

• 1 1/2 lb ground beef (80% lean)
• kosher salt, to taste
• freshly ground black pepper, to taste
• 4 slices American cheese
• 4 burger buns
• 2 tbsp unsalted butter, softened
• 2 medium yellow onions, thinly sliced
• 1 tbsp vegetable oil

Instructions

1. Heat the vegetable oil in a large cast iron skillet or griddle over medium heat. Add the sliced onions and cook, stirring occasionally, until deeply golden and caramelized, about 10 minutes. Season with a pinch of salt and pepper. Transfer to a bowl and set aside.
2. Spread the softened butter on the cut sides of the burger buns.
3. Heat the same skillet over medium-high heat. Place the buns cut-side down and toast until golden brown, about 1-2 minutes. Remove and set aside.
4. Divide the ground beef into 4 equal balls (about 6 ounces each). Heat the griddle over high heat until smoking hot. Place a ball of beef on the hot surface and immediately press down firmly with a flat spatula or burger press to form a thin patty, about 1/4 inch thick. Season generously with salt and pepper. Repeat with remaining beef.
5. Cook the patties without moving them for 2 minutes, until the edges are browned and the bottom is deeply caramelized. Carefully flip each patty and cook for another 1-2 minutes for medium doneness. Place a slice of American cheese on each patty during the last minute of cooking, allowing it to melt.
6. Place the toasted bottom buns on serving plates. Top each with a cooked patty, then a generous pile of caramelized onions. Finish with the top bun. Serve immediately.

Contains: gluten, milk

Estimated nutrition per serving

Calories

650

Protein

35 g

Carbohydrates

40 g

Fat

38 g

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