Preheat the oven to 350°F (175°C).

Lightly grease a casserole dish.

Place the chicken breasts in the prepared casserole dish.

Lay the Swiss cheese slices on top of the chicken breasts.

In a bowl, mix together the cream of mushroom soup and milk.

Pour the mixture over the chicken and cheese.

Spread the Pepperidge Farm herb seasoning stuffing mix evenly over the top of the chicken and soup mixture.

Drizzle the melted margarine over the stuffing mix.

Cover the casserole dish with aluminum foil and bake in the preheated oven for 40 minutes.

After 40 minutes, remove the foil and continue baking for an additional 10 minutes, or until the chicken is cooked through and the stuffing is golden brown.

Serve hot.