Mushroom Swiss Burger Onions (Printable Format)

Juicy beef patty topped with Swiss cheese, sautéed mushrooms, and caramelized onions on a toasted bun.

# What You 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 preferred)
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, salt, and sugar. Cook, stirring occasionally, for 18-20 minutes until onions are golden brown and caramelized. Remove from skillet and set aside.
02 - In the same skillet, heat butter and olive oil over medium-high heat. Add sliced mushrooms, salt, pepper, and thyme if using. Sauté for 6-8 minutes until mushrooms are browned and excess liquid evaporates. Remove and set aside.
03 - Divide ground beef into 4 equal portions and shape into patties slightly larger than the buns. Season both sides evenly with salt and pepper.
04 - Preheat grill or skillet to medium-high heat. Cook patties 3-4 minutes per side for medium doneness or to preference. During the last minute, top each patty with Swiss cheese and cover to melt.
05 - Optionally spread mayonnaise on bottom buns. Layer arugula or lettuce, followed by the cheeseburger patty, then spoon sautéed mushrooms and caramelized onions on top. Finish with the top bun.
06 - Serve the assembled burgers immediately while hot.

# Expert Suggestions:

01 -
  • Those caramelized onions melt into pure sweetness, making every bite taste indulgent without feeling heavy.
  • The sautéed mushrooms add an earthy depth that transforms a regular burger into something you'd actually pay premium prices for.
  • It comes together in under 45 minutes but tastes like you've been cooking all afternoon.
02 -
  • Don't skip the low-and-slow approach with the onions—high heat will just brown them instead of caramelizing them, and you'll miss that sweet, jammy texture.
  • If your mushrooms release a lot of liquid, don't panic; just keep cooking until it evaporates, or they'll make your burger soggy.
  • Season the beef gently when forming patties; overworking it makes tough, dense burgers instead of tender, juicy ones.
03 -
  • Toast your buns lightly in the same skillet as your mushrooms—they'll pick up those savory flavors and won't get soggy from the toppings.
  • If you're cooking for a crowd, prep your onions and mushrooms ahead of time and just reheat them gently while the burgers cook.

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