Preheat the oven to 350°F. Grease a 2- to 3-quart baking dish with cooking spray.
Stir together the first 5 ingredients and ½ cup of the butter until well blended.
Spoon into a greased 2- to 3-quart baking dish.
Crush the cereal, and stir in the remaining ¼ cup butter. Sprinkle over the potato mixture.
Bake at 350°F for 50 minutes.
