Heat a large skillet. Spread ½ tablespoon butter on one side of each slice of bread. Place 2 pieces of bread butter side down on the skillet.
Divide the dressing evenly on both pieces of bread. Top each slice of bread with 2 slices of swiss cheese. Add 4-5 slices of corned beef on top of each piece of bread. Divide the sauerkraut evenly between both slices then top with the remaining cheese. Place the last piece of bread butter side out on top.
Cover the skillet with a lid and cook for around 2-3 minutes, or until bread is golden. Flip and cook the other side for around 2-3 minutes.