# What You’ll Need:
→ Onions
01 - 2 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1 tablespoon olive oil
04 - 1/2 teaspoon kosher salt
05 - 1/4 teaspoon freshly ground black pepper
→ Patties
06 - 1 lb ground beef (80/20 blend preferred)
07 - 1 teaspoon Worcestershire sauce
08 - 1/2 teaspoon garlic powder
09 - 1/2 teaspoon kosher salt
10 - 1/4 teaspoon freshly ground black pepper
→ Assembly
11 - 8 slices rye bread
12 - 8 slices Swiss cheese
13 - 4 tablespoons unsalted butter, softened
# How To Make:
01 - Melt butter with olive oil in a large cast-iron skillet over medium heat. Add sliced onions, season with salt and pepper, and cook while stirring occasionally until deep golden brown and softened, approximately 20 minutes. Transfer onions to a bowl and wipe skillet clean.
02 - In a bowl, combine ground beef with Worcestershire sauce, garlic powder, salt, and pepper. Gently mix and shape into 4 thin, oval patties about the size of the bread slices.
03 - Heat the cleaned skillet over medium-high heat. Cook patties 2 to 3 minutes per side until well browned and just cooked through. Remove from skillet and set aside.
04 - Butter one side of each bread slice. On a flat surface, place 4 slices buttered side down. Layer each with 1 slice Swiss cheese, a beef patty, a generous spoonful of caramelized onions, another slice of Swiss cheese, then top with the remaining bread slices, buttered side up.
05 - Return skillet to medium heat. Place sandwiches in the skillet, pressing gently. Cook 3 to 4 minutes per side until bread is golden brown and cheese is melted, adding more butter if needed.
06 - Cut sandwiches in halves or quarters and serve immediately.
