# What You'll Need:
→ Onions
01 - 2 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1/2 teaspoon salt
04 - 1/4 teaspoon black pepper
→ Beef Patties
05 - 1 pound ground beef (80/20)
06 - 1 teaspoon Worcestershire sauce
07 - 1/2 teaspoon garlic powder
08 - 1/2 teaspoon salt
09 - 1/4 teaspoon black pepper
→ Sandwiches
10 - 8 slices rye bread
11 - 8 slices Swiss cheese
12 - 4 tablespoons unsalted butter, softened
# Steps:
01 - Heat 2 tablespoons of unsalted butter in a large cast-iron skillet over medium heat. Add the sliced onions, salt, and pepper. Cook, stirring occasionally, until onions become deeply golden and caramelized, about 15 to 20 minutes. Transfer to a bowl and set aside.
02 - In a mixing bowl, gently combine ground beef with Worcestershire sauce, garlic powder, salt, and black pepper. Form into 4 oval patties slightly larger than the bread slices.
03 - Increase heat to medium-high and wipe out the skillet. Add patties and cook for 3 to 4 minutes per side until browned and cooked through. Remove from skillet and set aside.
04 - Arrange rye bread slices on a work surface. On four slices, layer one slice of Swiss cheese, a cooked beef patty, a generous portion of caramelized onions, and another slice of Swiss cheese. Top each with the remaining bread slices.
05 - Wipe out the skillet and return to medium heat. Spread softened butter on the outside of each sandwich. Grill sandwiches in the skillet, working in batches if necessary, for 3 to 4 minutes per side, pressing gently, until the bread is golden brown and the cheese has melted.
06 - Slice each sandwich in half and serve immediately while hot.
