Mushroom Swiss Burger Caramelized Onions (Printable)
Juicy beef patty with melted Swiss, sautéed mushrooms, and sweet caramelized onions on a toasted bun.
# What You'll Need:
→ Burger
01 - 1.5 lbs ground beef (80/20 blend)
02 - 1 tsp kosher salt
03 - 0.5 tsp freshly ground black pepper
04 - 1 tbsp Worcestershire sauce
→ Caramelized Onions
05 - 2 large yellow onions, thinly sliced
06 - 1 tbsp unsalted butter
07 - 1 tbsp olive oil
08 - 0.5 tsp salt
09 - 1 tsp sugar (optional)
→ Sautéed Mushrooms
10 - 8 oz cremini or button mushrooms, sliced
11 - 1 tbsp unsalted butter
12 - 1 tbsp olive oil
13 - 1 clove garlic, minced
14 - 0.25 tsp salt
15 - 0.25 tsp black pepper
16 - 1 tsp fresh thyme leaves (optional)
→ Assembly
17 - 4 slices Swiss cheese
18 - 4 brioche or hamburger buns, split and toasted
19 - 4 tbsp mayonnaise or aioli (optional)
20 - Lettuce leaves (optional)
# How-To Steps:
01 - Melt butter and olive oil in a large skillet over medium heat. Add sliced onions, salt, and sugar if desired. Cook, stirring occasionally, for 15 to 20 minutes until golden and caramelized, reducing heat if browning too rapidly. Set aside.
02 - In a separate skillet over medium-high heat, melt butter and olive oil. Add mushrooms and cook 4 to 5 minutes until browned. Stir in garlic, salt, pepper, and thyme, cooking 1 to 2 minutes more. Remove from heat.
03 - Combine ground beef with salt, pepper, and Worcestershire sauce in a bowl. Gently mix and shape into 4 patties slightly larger than buns.
04 - Heat grill or skillet over medium-high heat. Cook patties 3 to 4 minutes per side for medium doneness. During the last minute, place a slice of Swiss cheese on each patty and cover to melt.
05 - Lightly toast buns on grill or in toaster until golden.
06 - Spread mayonnaise or aioli on bottom buns if desired. Add lettuce, burger patties, sautéed mushrooms, caramelized onions, and top with the bun crown. Serve immediately.
# Expert Advice:
01 -
- The caramelized onions are sweet and deep, nothing like raw onion on a burger.
- Sautéed mushrooms add an earthy richness that makes this feel restaurant-quality but requires no special skill.
- Everything comes together in one meal without complicated techniques or long waits.
02 -
- Don't press down on the burgers while they cook; it squeezes out all the good juices and flattens them.
- The cheese needs to melt in the last minute—if you add it too early, it can brown unevenly.
- Caramelizing onions truly takes time; there's no real shortcut, but the payoff is worth every minute.
03 -
- Toast your buns right before assembly so they're warm but not dry; timing matters more than you'd think.
- Keep your hands cold and work quickly when forming patties; warmth from your hands can toughen the meat.