Prepare the Patties: Shape the ground beef into four oval patties. Season with salt, pepper, and optional Worcestershire sauce. Cook in a medium-high heat skillet for about 4 minutes per side or until desired doneness. Set aside.
Caramelize Onions: In the same skillet, reduce heat to medium. Add a bit of butter if needed, and cook the sliced onions until caramelized, about 10 minutes, stirring occasionally.
Prep Bread: Butter one side of each slice of rye bread. These buttered sides will be the outer part of your sandwich, achieving that golden-brown toast upon cooking.
Assemble & Cook: Clear the skillet and assemble the Patty Melts: bread (buttered side down), slice of Swiss cheese, caramelized onions, beef patty, another slice of cheese, and top with another slice of bread (buttered side up). Cook over medium heat until each side is golden and the cheese melts, about 3 minutes per side.
Serving: Serve warm, cut in half to showcase the melted layers. Offer Thousand Island dressing on the side for an extra flavor dimension.
