# Components:
→ For the Patties
01 - 1 pound ground beef (80/20 blend)
02 - 1 teaspoon Worcestershire sauce
03 - 1/2 teaspoon garlic powder
04 - 1/2 teaspoon kosher salt
05 - 1/4 teaspoon freshly ground black pepper
→ For the Onions
06 - 2 large yellow onions, thinly sliced
07 - 2 tablespoons unsalted butter
08 - 1/4 teaspoon salt
→ For Assembly
09 - 8 slices rye bread
10 - 8 slices Swiss cheese
11 - 4 tablespoons unsalted butter, softened
12 - Optional: 2 tablespoons mayonnaise
# Method:
01 - Combine ground beef, Worcestershire sauce, garlic powder, salt, and pepper in a mixing bowl. Form into four equal patties, slightly larger than the bread slices.
02 - Heat a cast iron skillet over medium heat. Add 2 tablespoons butter, sliced onions, and salt. Cook stirring occasionally until golden and caramelized, about 12 to 15 minutes. Remove and set aside.
03 - Increase heat to medium-high. Add beef patties and cook 3 to 4 minutes per side until browned and cooked through. Remove and set aside.
04 - Wipe skillet clean. Butter one side of each bread slice. Place four slices, buttered side down, in the skillet. Layer with Swiss cheese, a beef patty, caramelized onions, another slice of Swiss cheese, then top with second bread slice buttered side up.
05 - Cook over medium heat until bread is golden and cheese melts, about 3 minutes per side. Press gently with spatula to develop an even crust.
06 - Slice each sandwich in half and serve immediately while hot.
