Mushroom Swiss Burger Onions (Printable)
Juicy beef patty topped with Swiss cheese, mushrooms, and caramelized onions on a toasted bun.
# What You'll Need:
→ Burgers
01 - 1 lb ground beef (80/20 blend preferred)
02 - 1 tsp kosher salt
03 - ½ tsp freshly ground black pepper
04 - 1 tsp Worcestershire sauce
→ Caramelized Onions
05 - 2 large yellow onions, thinly sliced
06 - 1½ tbsp unsalted butter
07 - 1 tbsp olive oil
08 - ½ tsp salt
09 - ½ tsp sugar
→ Mushrooms
10 - 8 oz cremini or button mushrooms, sliced
11 - 1 tbsp unsalted butter
12 - 1 clove garlic, minced
13 - ¼ tsp salt
14 - ¼ tsp black pepper
15 - 1 tsp fresh thyme leaves (optional)
→ Assembly
16 - 4 slices Swiss cheese
17 - 4 brioche or hamburger buns, split
18 - 2 tbsp mayonnaise (optional)
19 - Lettuce leaves (optional)
# How-To Steps:
01 - In a large skillet over medium heat, melt butter with olive oil. Add sliced onions, sprinkle with salt and sugar, then cook stirring frequently for 20-25 minutes until deeply golden and caramelized. Transfer to a bowl and set aside.
02 - In the same skillet, melt butter over medium heat. Add mushrooms and cook for 6-8 minutes until they release moisture and start browning. Add garlic, salt, pepper, and thyme if using; sauté for 1-2 minutes more. Set aside.
03 - Gently combine ground beef with Worcestershire sauce, salt, and pepper in a bowl. Divide into 4 equal patties, making a slight indentation in the center of each.
04 - Heat grill or skillet over medium-high heat. Cook patties 3-4 minutes per side for medium doneness. In the final minute, top each patty with Swiss cheese slice and cover to melt.
05 - Lightly toast bun halves on the grill or in a toaster until golden.
06 - Spread mayonnaise on bottom buns if using, add lettuce if desired, then place patties, sautéed mushrooms, caramelized onions, and top with bun halves. Serve immediately.
# Expert Advice:
01 -
- Those caramelized onions transform from ordinary to liquid gold, sweet and jammy in a way that makes everything taste fancier.
- The mushrooms soak up garlic and butter until they're almost meaty, giving you layers of flavor in every bite.
- It feels like restaurant food, but you're making it at home in less than an hour with ingredients you probably already have.
02 -
- Don't skip the indent in the center of your patty—it keeps the burger from puffing up like a dome and ensures even cooking.
- Caramelized onions need patience and a moderate heat; crank the temperature too high and they'll burn before they sweeten.
03 -
- Toast your buns right before assembling so they're warm and give structural support to all that wonderful stuff piled on top.
- If you have time, make the caramelized onions and mushrooms ahead—they actually taste better the next day and you can reheat them gently while the burgers cook.