1. Place soft pretzels flat on work surface and cut in half across the width. Spread each cut side with Thousand Island dressing.
2. Layer bottoms of pretzels with Swiss cheese, sauerkraut, corned beef, and another layer of cheese. Place other halves of each pretzel on top of each sandwich.
3. Place large cast-iron skillet over medium-high heat. Once hot, add 1 tablespoon butter and swirl to melt. Place 2 sandwiches upside-down in pan, and cook 2 to 3 minutes, until cheese is starting to melt. Flip and cook additional 2 to 3 minutes, until cheese is melted. Remove from skillet and repeat with remaining butter and sandwiches.