Mushroom Swiss Burger Caramelized Onions (Printable)
Juicy beef layered with Swiss cheese, sautéed mushrooms, and sweet caramelized onions on toasted buns.
# What You'll Need:
→ Caramelized Onions
01 - 2 large yellow onions, thinly sliced
02 - 2 tbsp unsalted butter
03 - 1 tbsp olive oil
04 - 1/2 tsp salt
05 - 1/2 tsp sugar
→ Mushrooms
06 - 9 oz cremini or button mushrooms, sliced
07 - 1 tbsp unsalted butter
08 - 1 tbsp olive oil
09 - 1/4 tsp salt
10 - 1/4 tsp black pepper
11 - 1 tsp fresh thyme leaves (optional)
→ Burgers
12 - 1.3 lbs ground beef (80/20 blend recommended)
13 - 1 tsp salt
14 - 1/2 tsp black pepper
15 - 4 slices Swiss cheese
16 - 4 burger buns, split and toasted
17 - 2 tbsp mayonnaise (optional)
18 - 2 cups fresh arugula or lettuce leaves
# How-To Steps:
01 - Heat butter and olive oil in a large skillet over medium-low heat. Add sliced onions along with salt and sugar, and cook, stirring occasionally, for 18 to 20 minutes until golden and caramelized. Remove from heat and set aside.
02 - In the same skillet, heat butter and olive oil over medium-high heat. Add sliced mushrooms, salt, black pepper, and thyme if using. Sauté for 6 to 8 minutes until mushrooms are browned and moisture has evaporated. Remove from heat.
03 - Divide ground beef into four equal portions and shape each into a patty slightly larger than the buns. Season both sides with salt and black pepper.
04 - Preheat grill or skillet to medium-high heat. Cook patties 3 to 4 minutes per side for medium doneness or to preference. During the final minute of cooking, place one slice of Swiss cheese on each patty and cover to melt the cheese.
05 - If desired, spread mayonnaise on the bottom halves of the toasted buns. Layer arugula or lettuce leaves, then the cheeseburger patties, followed by a generous amount of sautéed mushrooms and caramelized onions. Top with the other bun halves.
06 - Serve immediately while hot for the best flavor and texture.
# Expert Tips:
01 -
- The caramelized onions do all the heavy lifting of flavor, making this burger feel restaurant-quality with minimal fuss.
- Everything except the actual patty can be prepped ahead, so you're really just grilling and assembling when guests arrive.
- Swiss cheese melts into these silky ribbons that play beautifully against the earthiness of the mushrooms.
02 -
- Caramelized onions aren't something you can rush—medium-low heat and patience create the sweetness; high heat just burns them bitter and angry.
- Don't season your beef patties until right before cooking, because salt draws out moisture and can make them tough if it sits for too long.
- Mushrooms release a lot of water as they cook, so make sure your pan is hot enough to evaporate it and actually brown them instead of just steaming.
03 -
- A splash of balsamic vinegar in the final two minutes of caramelizing the onions adds an unexpected depth that guests will taste but can't quite place.
- If you're feeling adventurous, try pressing a small indent into the top of your patty with your thumb as it cooks—it keeps the burger flat and level instead of bulging in the middle.