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Mushroom Swiss Patty Melt

A luxurious and flavorful sandwich featuring caramelized onions, sautéed mushrooms, and a beef patty, all layered between buttery toasted rye bread and melted Swiss cheese.
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Prep Time 10 minutes
Cook Time 35 minutes
Total Time 45 minutes
Servings: 4 sandwiches
Course: Dinner, Lunch
Cuisine: American
Calories: 650
Ingredients Method Notes

Ingredients
  

For the Beef Patties
  • 450 g 80/20 ground beef Divided into 4 equal portions
  • 1 teaspoon garlic powder
  • 1 teaspoon onion powder
  • 1/2 teaspoon smoked paprika
  • 1 teaspoon Worcestershire sauce
  • Salt and freshly cracked black pepper To season just before cooking
For the Sautéed Mushrooms
  • 300 g cremini or baby bella mushrooms Cleaned and sliced 5mm thick
  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 2 cloves garlic, finely minced
  • 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried)
  • 1 tablespoon soy sauce or Worcestershire sauce (for depth)
  • Salt and black pepper To taste
For the Caramelised Onions
  • 2 large yellow onions Peeled and thinly sliced into half-moons
  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1 teaspoon granulated sugar (to assist caramelisation)
  • 1/2 teaspoon salt
  • 1 tablespoon balsamic vinegar (added at the end)
For Assembly
  • 8 slices rye bread (marble rye or dark rye both work beautifully)
  • 8 slices Swiss cheese (about 200g total)
  • 4 tablespoons softened unsalted butter (for toasting the bread)
  • 2 tablespoons Dijon mustard or mayonnaise (spread on the inner bread faces, optional but recommended)

Method
 

Preparation
  1. Start by caramelizing the onions: heat the butter and olive oil in a skillet over medium heat, add sliced onions, salt, and sugar. Cook on medium-low for 25–30 minutes, stirring occasionally.
  2. For the mushrooms, in a separate skillet, heat butter and olive oil over medium-high heat, add sliced mushrooms in a single layer. Do not stir for the first 2-3 minutes. Then stir, add minced garlic and thyme, and cook for another minute.
  3. For the beef patties, divide beef into four portions and mix in seasoning gently without overworking. Form loosely into balls.
Cooking
  1. Heat a skillet over high heat, add oil, and cook the beef balls by smashing them flat. Cook for 3-4 minutes on one side without disturbing.
  2. Flip the patties, cook for 2 minutes, then add Swiss cheese on top, cover to melt.
  3. Toast the assembled sandwiches in the skillet with butter until golden and crispy on both sides.
Serving
  1. Remove from heat, let rest for 60 seconds, slice diagonally and serve immediately.

Notes

Store caramelised onions and sautéed mushrooms in the fridge for up to 4 days. Cooked patties can be reheated, but assembled sandwiches do not store well. Use Dijon mustard for added flavor.