1. Lightly spread butter on one side of each slice of bread.
2. Prepare Thousand Island Dressing.
Thousand Island Dressing:
Combine 1/2 cup mayonnaise, 1/2 cup ketchup, 1/4 cup drained sweet pickle relish, 2 teaspoons distilled white vinegar and 1 teaspoon Worcestershire sauce in medium bowl. Cover and refrigerate at lease 1 hour.
3. Heat large nonstick skillet over medium heat until hot. Place 2 bread slices, butter side down, in skillet. Top each bread slice with 1 tablespoon dressing, 3 ounces corned beef, quarter of sauerkraut and 2 cheese slices. Top with 2 bread slices butter side up.
4. Cook sandwiches 4 to 6 minutes or until bread is golden brown and cheese is melted, turning once. Repeat with remaining bread, dressing, corned beef, sauerkraut and cheese. Serve with additional Thousand Island Dressing, as desired.