01 -
Preheat the oven to 350°F. Grease a 9-by-13-inch baking dish with cooking spray or a little butter.
02 -
Spread the cooked chicken in an even layer in the baking dish. Arrange the Swiss cheese slices over the chicken, overlapping slightly if needed.
03 -
In a bowl, whisk together the condensed soup, sour cream, milk, garlic powder, black pepper, and a small pinch of salt only if needed. Spread the sauce evenly over the cheese.
04 -
Toss the stuffing mix with melted butter and chicken broth or water until the bread pieces are lightly coated. Sprinkle the mixture evenly over the casserole.
05 -
Cover the dish with foil and bake on the center rack for 25 minutes, until the filling is hot and starting to bubble around the edges.
06 -
Remove the foil and bake 8-10 minutes more, until the topping is lightly golden. Rest for 5-10 minutes before serving.