#### 1. Preheat the oven:
Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish or spray it with cooking spray.
#### 2. Prepare the chicken:
Season the chicken breasts with garlic powder, onion powder, salt, and pepper. Arrange them in a single layer in the prepared baking dish.
#### 3. Add the cheese:
Place slices of Swiss cheese over each chicken breast, covering the surface evenly.
#### 4. Make the creamy sauce:
In a mixing bowl, whisk together the cream of chicken soup, sour cream, and milk until smooth. Pour the mixture evenly over the chicken and cheese.
#### 5. Prepare the stuffing topping:
In a separate bowl, combine the stuffing mix with the melted butter. Toss until the stuffing is evenly coated. Spread the stuffing mixture over the top of the casserole.
#### 6. Bake:
Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15–20 minutes, or until the chicken is cooked through (internal temperature of 165°F/74°C) and the stuffing is golden brown.