Preheat the oven to 350ºF (177ºC) and lightly grease a medium-sized baking dish (7.5 X 10” or 9X9”).

Place the chicken breasts in the baking dish, spacing them evenly. Season to taste with salt and pepper, and set aside.

In a bowl, combine the cream of chicken soup and sour cream, stirring well until smooth.

Spread the soup mixture evenly over the chicken breasts in the baking dish.

Place 6 slices of Swiss cheese on top of the soup layer, covering the chicken thoroughly.

Sprinkle the dry stuffing mix over the casserole, ensuring it covers the entire surface.

Drizzle the melted butter over the stuffing layer for extra flavor and crispiness.

Cover the baking dish tightly with aluminum foil and place it in the oven.

Bake for 50-80 minutes, until the chicken juices run clear and the internal temperature reaches 165ºF (74ºC) in the thickest part of each piece. Remember, larger pieces may take longer, while smaller pieces will cook faster. Uncover halfway through baking (25-40 minutes) to allow the topping to crisp up.