Mushroom Swiss Burger Caramelized Onions (Printable)
Juicy beef burger featuring sautéed mushrooms, melted Swiss, and caramelized onions on a toasted bun.
# What You'll Need:
→ Burgers
01 - 1.5 lbs ground beef (80/20 blend recommended)
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 - In a large skillet over medium heat, melt butter and olive oil. Add sliced onions and salt, along with sugar if using. Cook, stirring occasionally, for 15 to 20 minutes until onions are deeply golden and caramelized. Reduce heat as necessary to avoid burning. Set aside.
02 - In a separate skillet over medium-high heat, melt butter and olive oil. Add mushrooms and cook for 4 to 5 minutes until browned. Stir in garlic, salt, pepper, and thyme if using; continue cooking for 1 to 2 minutes. Remove from heat.
03 - Gently combine ground beef with salt, pepper, and Worcestershire sauce in a bowl. Shape mixture into 4 evenly sized patties, slightly larger than the buns.
04 - Preheat grill or skillet to medium-high heat. Cook patties for 3 to 4 minutes per side for medium doneness, longer if preferred. In the final minute, top each patty with a slice of Swiss cheese and cover to melt.
05 - Lightly toast brioche or hamburger buns on the grill or in a toaster until golden.
06 - Optional: spread mayonnaise or aioli on bottom buns. Layer with lettuce if desired, place burger patties, then sautéed mushrooms and caramelized onions. Finish with top bun and serve immediately.
# Expert Advice:
01 -
- The caramelized onions add a sweet, jammy richness that makes every bite feel indulgent without any fuss.
- It comes together in under an hour but tastes like you spent all day on it, which is exactly the kind of trick I love pulling off.
02 -
- Don't rush the onions or crank up the heat to speed things up, because they'll burn instead of caramelize and turn bitter.
- Press a small dimple into the center of each patty before cooking so they don't puff up into little domes on the grill.
03 -
- Let the patties rest for a minute after cooking so the juices redistribute instead of running all over your plate.
- If you're cooking for a crowd, keep the onions and mushrooms warm in a low oven while you finish the burgers so everything stays hot.