French Onion Smash Burgers (Print View)

Smashed beef patties layered with caramelized onions and melted cheese served on soft slider buns.

# Components:

→ Meats

01 - 1.1 pounds ground beef (80/20 blend)

→ Vegetables

02 - 3 large yellow onions, thinly sliced
03 - 2 tablespoons unsalted butter
04 - 1 tablespoon olive oil
05 - 1 teaspoon fresh thyme leaves (optional)

→ Breads & Dairy

06 - 8 slider buns
07 - 8 slices Gruyère or Swiss cheese

→ Condiments & Seasoning

08 - 1 tablespoon Worcestershire sauce
09 - 1 teaspoon kosher salt
10 - ½ teaspoon freshly ground black pepper
11 - 2 tablespoons mayonnaise (optional)
12 - 1 tablespoon Dijon mustard (optional)

# Method:

01 - Melt butter and olive oil in a large skillet over medium heat. Add sliced onions with a pinch of salt and cook, stirring occasionally, until golden brown and caramelized, approximately 25 to 30 minutes. In the last minutes, stir in Worcestershire sauce and thyme if desired. Set aside and keep warm.
02 - Divide the ground beef into 8 equal portions of about 2 ounces each. Season each portion evenly with kosher salt and black pepper.
03 - Heat a cast iron skillet or griddle over medium-high heat. Place the beef portions on the surface and immediately press each firmly with a spatula to form thin patties.
04 - Cook the patties for 2 minutes without moving, then flip. Immediately top each with a generous spoonful of caramelized onions followed by a slice of cheese. Cover the skillet briefly to allow the cheese to melt, about 1 minute.
05 - While the patties finish cooking, toast the slider buns cut side down in a dry skillet or under a broiler until lightly golden.
06 - Spread mayonnaise and/or Dijon mustard on the toasted buns if desired. Place each cheesy patty with onions onto the bottom bun, then top with the bun crown. Serve immediately.

# Expert Advice:

01 -
  • Caramelizing a mountain of onions feels like kitchen magic, and the reward is unbelievably deep, sweet flavor on every bite.
  • It’s a crowd-pleaser that turns simple ingredients into something that tastes like you’ve spent hours behind the stove—without the stress.
02 -
  • Rushing the onions results in pale, stringy bits—let patience do its work until they’re deep bronze and tasting almost jammy.
  • Tenting the burgers to melt the cheese fully is a game-changer—no sad, half-melted slices here.
03 -
  • Press the patties thin for extra crispy edges—it’s the hallmark of a killer smash burger.
  • A dab of beef broth in the onions midway boosts richness—a trick I never skip now.
Return