Day before mashed potatoes recipe in the thanksgiving category

: Bring a large pot of salted water to a boil. Drop in potatoes and cook until tender but still firm, about 15 minutes. Transfer potatoes to a large bowl and mash until smooth. Mix in the cream cheese, sour cream, onion powder, salt, pepper and butter. Cover and refrigerate 8 hours, or overnight. Preheat oven to 350F. Lightly grease a medium baking dish. Spread potato mixture into the prepared baking dish. Bake in the preheated oven about 30 minutes.