Mushroom Swiss Burger Onions (Printable)
Juicy beef burger with sautéed mushrooms, melted Swiss cheese, and sweet caramelized onions on a toasted bun.
# What You’ll 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 oz 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 lbs 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 deeply golden and soft, about 20 minutes. Stir in balsamic vinegar during the last 2 minutes, if using. Remove from heat 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, approximately 7 minutes. Add minced garlic, season with salt and pepper, and cook for 1 more minute. Remove from heat and set aside.
03 - Form ground beef into 4 equal patties about 3/4 inch thick. Season both sides evenly with salt and black pepper.
04 - Preheat grill or skillet over medium-high heat. Cook patties for 3 to 4 minutes per side for medium doneness or until preferred temperature. During the last minute of cooking, place a slice of Swiss cheese on each patty and cover to allow melting.
05 - Spread softened butter on the cut sides of the buns. Toast them on a skillet or grill, cut side down, until golden brown.
06 - Place lettuce and tomato slices on the bottom bun if desired. Add the cheese-topped patties, then layer sautéed mushrooms and caramelized onions. Spread Dijon mustard or mayonnaise on the top bun if using. Close the sandwich and serve immediately.
# Expert Advice:
01 -
- The caramelized onions add an almost sweet, savory depth that feels way fancier than the effort requires.
- Stacking sautéed mushrooms and melted Swiss cheese together creates this umami-rich experience that elevates ground beef from casual to crave-worthy.
- You can have everything ready and just assemble at the end, which makes feeding people feel easy.
02 -
- Never press down on your burgers while they cook—it squeezes out the juices and leaves you with a hockey puck instead of a tender patty.
- The 80/20 ground beef blend matters more than you'd think; too lean and the burger tastes dry, too fatty and it shrinks dramatically in the pan.
- Those caramelized onions need time; if you rush them on high heat, they'll scorch and taste bitter instead of sweet.
03 -
- Make your caramelized onions ahead of time—they keep in the fridge for days and actually taste better the next day once the flavors have had time to settle.
- If your mushrooms release too much liquid, don't panic; just let them cook a bit longer and the moisture will evaporate, concentrating their earthy flavor.