This Slow Cooker Chicken Reuben Casserole is a delicious twist on the classic Reuben sandwich. Tender chicken, sauerkraut, Swiss cheese, and Thousand Island dressing are layered together and slow-cooked to perfection. The result is a comforting and flavorful casserole that is perfect for a weeknight dinner or potluck. Serve it with rye bread or over a bed of mashed potatoes for a complete meal.