Go Back Email Link
–+ servings
A Mushroom Swiss Burger topped with sautéed mushrooms and onions on a white plate, served with crispy French fries.

Mushroom Swiss Burger with Caramelized Onions

Yield: 4 servings
Prep Time: 10 minutes
Cook Time: 1 hour
Total Time: 1 hour 10 minutes
If there’s one burger I come back to time and time again, it’s this mushroom swiss burger. There’s just something about the way juicy beef, melty Swiss cheese, and buttery sautéed mushrooms come together that hits every craving. I tuck it all into a soft, toasted brioche bun and pile on a generous scoop of sweet, jammy caramelized onions for good measure. It’s rich, savory, and a total classic—and I promise, it’s worth every bite.

Ingredients

  • 1 ½ tablespoons butter, plus more for the buns
  • 2 large yellow onions, vertically sliced - see notes
  • 1 teaspoon salt, divided
  • 1 ½ lb lean ground beef
  • 1 tablespoon olive oil
  • 8 ounces crimini mushrooms, sliced
  • 4 thick slices swiss cheese
  • 4 brioche buns
  • Mayonnaise and butter lettuce

Instructions 

  • Melt the butter in a large, cast-iron frying pan over medium-high heat. As soon as it's melted, add the onions and stir. Cook for 8-10 minutes, stirring occasionally, until the onions have softened.
    1 ½ tablespoons butter, 2 large yellow onions
    Image for recipe instruction: A cast iron skillet filled with raw, thinly sliced white onions—perfect for topping a Mushroom Swiss Burger—sits on a beige countertop.
  • Lower the heat to medium, stir in ¼ teaspoon of the salt, and continue to cook, stirring occasionally, for 30-50 minutes, depending on how dark you'd like your onions. If the fond (the bits stuck to the pan) gets too dark or the onions are browning too quickly, add a splash of water to the pan.
    Image for recipe instruction: A cast iron skillet filled with golden-brown caramelized onions—perfect for topping a Swiss Burger or adding rich flavor to your favorite burger—sits on a light-colored countertop.
  • While the onions are cooking, slice the mushrooms and form the beef into 4 patties.
    1 ½ lb lean ground beef
    Image for recipe instruction: Sliced mushrooms and four raw beef burger patties are arranged on a wooden cutting board, perfect for creating a delicious Mushroom Swiss Burger.
  • When the onions are golden, remove them from the pan and increase the heat to medium. Add the olive oil and mushrooms and cook, stirring occasionally, for 10 minutes, until they are soft and starting to brown. Season with ¼ teaspoon of salt, add pepper to taste, and remove them from the pan.
    1 tablespoon olive oil, 8 ounces crimini mushrooms
    Image for recipe instruction: Sliced mushrooms sautéing in a black cast iron skillet on a light-colored countertop—perfect for topping a juicy Swiss Burger.
  • Increase the heat to medium-high, add the burger patties, and season them with the remaining ½ teaspoon of salt. Cook until the bottoms have a nice crust, about 3-4 minutes, then flip the burgers and cook until they reach an internal temperature of 165 degrees Fahrenheit, about 3-4 minutes more. Add Swiss cheese during the last 2 minutes of cooking, then remove the burgers from the pan.
    4 thick slices swiss cheese
    Image for recipe instruction: Four burger patties topped with melted swiss cheese sizzle in a black cast iron skillet, perfect for creating a delicious Mushroom Swiss Burger on a light-colored surface.
  • Wipe out the pan with a paper towel. Butter the brioche buns and toast them in the pan, working in batches.
    4 brioche buns
    Image for recipe instruction: A cast iron skillet with two burger buns cut in half, showing two tops and two bottoms, ready to be transformed into a delicious Mushroom Swiss Burger on a light-colored surface.
  • Spread mayonnaise (or your favorite burger sauces) on the buns, add a piece of lettuce, and top with a burger, onions, and mushrooms and serve right away.
    Mayonnaise and butter lettuce
    Image for recipe instruction: A plate of food featuring a delicious Mushroom Swiss Burger served with crispy fries.

Notes

How to slice onions: Start by vertically slicing your onions. Cut both ends off the onion, rest it on one of the cut ends, cut it in half, and then peel the onion. Lay the onion halves on your cutting board and then make slices going in the same direction as the grain – NOT into half moons. Slice until you get to the center of the onion half, then turn it down so that it's not so high and easier to cut. 
Serving: 1 = 1 burger, Calories: 468kcal, Carbohydrates: 31g, Protein: 43g, Fat: 18g, Saturated Fat: 8g, Polyunsaturated Fat: 2g, Monounsaturated Fat: 8g, Trans Fat: 1g, Cholesterol: 118mg, Sodium: 948mg, Potassium: 1007mg, Fiber: 2g, Sugar: 7g, Vitamin A: 141IU, Vitamin C: 6mg, Calcium: 115mg, Iron: 6mg