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