Ready, Set, Cook! Hidden Valley Contest Entry. Using a variation in the type of potatoes and onions I usually use to prepare this dish, I developed this recipe based on my choices listed in the rules. I tend to use Hidden Valley products often in my recipes, therefore it was easy to experiment and come up with this "scrumptious" tasting potato casserole. I do substitute low-calorie and add vegetables when I can, to get my family to eat more vegetables.