01 - Combine mayonnaise, ketchup, horseradish, pickle relish, Worcestershire sauce, salt, and pepper in a mixing bowl. Stir until thoroughly blended.
02 - Lay out rye bread slices and spread Russian dressing on one side of each slice.
03 - On two bread slices, arrange one slice of Swiss cheese, half the corned beef, half the sauerkraut, then top each with another slice of Swiss cheese.
04 - Place remaining bread slices, dressing side down, over the fillings to complete the sandwiches.
05 - Generously spread softened butter on the outside of each sandwich.
06 - Warm a skillet or griddle over medium heat. Cook sandwiches for 3 to 4 minutes per side, pressing gently, until the bread turns golden and cheese melts.
07 - Remove sandwiches from heat, halve, and serve immediately.