Spread one side of each bread slice with ½ tablespoon butter.
In a large non-stick skillet, over medium-low heat, arrange 2 slices of bread, buttered side down.
Spread 2 tablespoons of Russian dressing on each slice of bread; top each with ¼ pound corned beef, ¼ cup sauerkraut and 2 slices cheese.
Top each with 1 slice of bread, buttered side up.
Cook until golden and crispy underneath; about 5 minutes.
Flip the sandwiches and cook, pressing down gently with a spatula, until second side is golden and cheese melts; about 3 minutes more.
Transfer sandwiches to plates and wipe out skillet.
Repeat with the remaining bread, sauce, corned beef, sauerkraut and cheese.
Best if served warm.