Mushroom Swiss Patty Melt 
Ingredients:
1 lb ground beef (80/20 blend for juiciness)
Salt and black pepper to taste
1 tbsp olive oil
1 cup mushrooms, sliced
1 medium onion, thinly sliced
4 slices Swiss cheese
4 slices rye or sourdough bread
2 tbsp butter (for toasting the bread)
1/4 cup mayonnaise (optional)
1 tsp Dijon mustard (optional)
Directions:
Prepare the Patties: In a bowl, combine the ground beef, Worcestershire sauce, salt, and black pepper. Mix gently, then form the beef into 2 thin patties, pressing down slightly in the center to ensure even cooking.
Sauté the Mushrooms and Onions: Heat the olive oil in a skillet over medium heat. Add the sliced mushrooms and onions. Cook, stirring occasionally, until they are tender and caramelized, about 8-10 minutes. Remove from the skillet and set aside.
Cook the Beef Patties: In the same skillet, cook the beef patties for 4-5 minutes per side, or until they reach your desired doneness. Once cooked, remove them from the skillet and set aside.
Toast the Bread: Butter one side of each slice of bread. Optionally, spread mayonnaise and Dijon mustard on the unbuttered side. In a separate skillet or on a griddle, toast the bread, buttered side down, over medium heat until golden and crispy, about 2-3 minutes per side.
Assemble the Patty Melt: Place a slice of Swiss cheese on the unbuttered side of each slice of bread. Add a cooked beef patty on top of one slice. Top with the sautéed mushrooms and onions, then add another slice of Swiss cheese on top. Place the second slice of bread on top, buttered side out.
Grill the Sandwich: Return the sandwich to the skillet and grill over medium heat for about 3-4 minutes per side, pressing gently with a spatula, until the bread is golden brown and the cheese is melted.
Serve: Remove the sandwich from the skillet and slice it in half. Serve immediately with pickles or your favorite dipping sauce.
Enjoy