Preheat your oven to 375°F and lightly spray a 9×13 inch baking dish with nonstick cooking spray.
In a medium bowl, combine the sour cream, garlic powder, seasoned salt, pepper, and 1 cup of Parmesan cheese, mixing until smooth.
Arrange the chicken breasts evenly in the prepared baking dish in a single layer.
Spread the sour cream mixture over the chicken breasts, covering them completely from edge to edge.
Sprinkle the remaining 1/2 cup Parmesan cheese evenly on top.
Bake for 25-30 minutes until the chicken is thoroughly cooked and reaches an internal temperature of 165°F. Thicker breasts may need an additional 5 minutes.
Switch the oven to broil and place the pan under the broiler for 2-3 minutes until the top is lightly golden brown, watching carefully.
Serve immediately while the topping is bubbly.