Mushroom Swiss Burger Caramelized Onions (Print Version)

Juicy beef patty with sautéed mushrooms, melted Swiss cheese, and sweet caramelized onions on a toasted bun.

# What You Need:

→ Caramelized Onions

01 - 2 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1 tablespoon olive oil
04 - 1/2 teaspoon salt
05 - 1/2 teaspoon sugar
06 - 1 tablespoon balsamic vinegar (optional)

→ Mushrooms

07 - 9 ounces cremini or button mushrooms, sliced
08 - 1 tablespoon unsalted butter
09 - 1 tablespoon olive oil
10 - 1 clove garlic, minced
11 - Salt and pepper, to taste

→ Burgers

12 - 1.3 pounds ground beef (80/20 blend)
13 - 1 teaspoon salt
14 - 1/2 teaspoon black pepper
15 - 4 slices Swiss cheese
16 - 4 brioche or hamburger buns
17 - 1 tablespoon unsalted butter, softened (for toasting buns)

→ Optional Toppings

18 - Fresh lettuce leaves
19 - Sliced tomatoes
20 - Dijon mustard or mayonnaise

# How to Make It:

01 - Melt butter with olive oil in a large skillet over medium heat. Add sliced onions, salt, and sugar; cook, stirring frequently, until onions are golden and soft, about 20 minutes. Stir in balsamic vinegar during the last 2 minutes if using. Remove and set aside.
02 - In a separate skillet over medium-high heat, melt butter with olive oil. Add mushrooms and cook until browned and tender, about 7 minutes. Add minced garlic, season with salt and pepper, and cook for an additional minute. Remove and set aside.
03 - Divide ground beef into 4 equal portions and shape into patties approximately 3/4 inch thick. Season both sides evenly with salt and black pepper.
04 - Preheat grill or skillet over medium-high heat. Cook patties 3–4 minutes per side for medium doneness or to preferred temperature. During the last minute, top each patty with a slice of Swiss cheese and cover to melt.
05 - Spread softened butter on the cut sides of buns. Toast them cut side down on a skillet or grill until golden brown.
06 - Place fresh lettuce and sliced tomato on the bottom bun. Add the melted cheese-topped patty, followed by sautéed mushrooms and caramelized onions. Spread Dijon mustard or mayonnaise on the top bun if desired, then close the burger and serve immediately.

# Expert Hints:

01 -
  • The caramelized onions add a sweetness that transforms a simple burger into something restaurant-worthy.
  • Swiss cheese melts into every crevice of the patty, creating a savory blanket that holds the toppings together.
  • You can prep the onions and mushrooms ahead, so assembly becomes the easiest part of dinner.
02 -
  • Don't skip the caramelization step or rush it on high heat—low and slow turns onions sweet and mellow, while speed makes them bitter and tough.
  • If you overwork the burger meat when shaping, you'll end up with dense, rubbery patties instead of tender, juicy ones; handle the beef as little as possible.
  • Toast the buns every time, even if you think you'll skip it—they make the difference between a burger that holds together and one that falls apart.
03 -
  • If you're cooking for a crowd, caramelize the onions and sauté the mushrooms earlier in the day and gently reheat them just before serving—this saves you from juggling multiple pans at the last minute.
  • The 80/20 beef blend is non-negotiable; it cooks to a perfect pink center without being greasy or dry, and the beef flavor stays pronounced and beefy.

Go Back