Preheat Oven 350. Peel and Slice potatoes, precook for appr. 10-15 minutes on medium heat. While potatoes cook mix Perfectly Potato Cheddar Soup Mix, Milk, Water, Onion Onion, Seasoned Salt, Pepper and 3/4 Shredded Cheddar Cheese in large saucepan over medium heat till well mixed and cheese is melted. Spray 9 x 13 Baking Dish with Cooking Spray. Drain Potatoes, pour into Baking Dish. Pour Sauce Mixture over Potatoes and sprinkle remaining Shredded Cheese on top. Bake at 350 for 45 minutes.