Mushroom Swiss Burger Onions (Printable Version)

Savory beef burger topped with mushrooms, Swiss cheese, and caramelized onions, served 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)

# Step-by-Step:

01 - Melt butter with olive oil in a large skillet over medium heat. Add sliced onions, salt, and sugar. Cook, stirring frequently, for 20-25 minutes until deeply golden. Transfer to a bowl and set aside.
02 - In the same skillet, melt butter over medium heat. Add mushrooms and cook 6-8 minutes until browned and moisture evaporates. Stir in garlic, salt, pepper, and thyme (if using), sauté an additional 1-2 minutes. Set aside.
03 - Combine ground beef with Worcestershire sauce, kosher salt, and black pepper gently. Divide into 4 equal portions, pressing a slight indent in the center of each patty.
04 - Heat grill or skillet to medium-high. Cook patties for 3-4 minutes per side for medium doneness. In the last minute, top each with Swiss cheese and cover to melt.
05 - Lightly toast split buns on the grill or toaster until golden.
06 - Spread mayonnaise on bottom buns if using. Layer lettuce, burger patties, sautéed mushrooms, caramelized onions, and top with bun halves. Serve immediately.

# Expert Advice:

01 -
  • Every bite has something going on, from the earthiness of the mushrooms to the mellow sweetness of those slow-cooked onions
  • It feels fancy but uses ingredients you probably already have or can grab on a quick grocery run
  • The Swiss melts into every crevice and makes the whole thing taste richer without being heavy
02 -
  • Don't rush the onions or crank up the heat, they'll burn instead of caramelize and you'll lose all that sweetness
  • Press a dimple into each patty before cooking or they'll puff up like little domes and slide around on the bun
  • Let the mushrooms cook undisturbed for a few minutes so they get a real sear instead of steaming in their own liquid
03 -
  • Season the outside of the patties right before they hit the heat, not while shaping them, so the salt doesn't draw out moisture too early
  • If your onions start sticking, add a splash of water to the pan and scrape up the browned bits for even more flavor
  • Don't press down on the burgers while they cook, you'll squeeze out all the juices and end up with a dry patty

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