Add 2 pounds of chicken breasts to the bottom of a 6qt slow cooker.
Top the chicken breasts with the slices of Swiss cheese, breaking the slices into pieces to cover each chicken breast if needed.
Add the condensed Cream of Chicken soup to a small bowl. Add in the sour cream and stir well until combined.
Pour the sour cream and soup mixture on top of the chicken breasts, spreading it out evenly with the back of a silicone spatula or spoon.
Sprinkle on the entire contents of a 6oz box of dry stuffing mix, ensuring it is evenly distributed.
Pour ¼ cup of melted butter over the surface of the dry stuffing mix.
Place the lid on the slow cooker and cook on "low for 5-6 hours, or on "high" for 2 ½-3 hours. To ensure the chicken is cooked through, use an internal thermometer to check the temperature of each chicken breast. You are looking for a minimal internal temperature of 165F.
Serve and enjoy with your favorite side dishes!