Preheat a large skillet or griddle over medium heat while preparing the sandwiches.
Spread Thousand Island dressing evenly on one side of each slice of rye bread.
On half of the bread slices, layer a slice of Swiss cheese, corned beef, a portion of drained sauerkraut, and another slice of Swiss cheese. Place the remaining bread slices on top with the dressing facing inward.
Spread softened butter over the outside of each sandwich so both top and bottom surfaces are coated.
Place the sandwiches on the hot skillet with the buttered side down. Cook until the bread turns golden brown and crisp, then carefully flip and continue cooking until the second side is equally browned and the cheese has melted.
Remove from the skillet, slice if desired, and serve while hot.