Crockpot Parmesan Ranch Mushrooms | Excellent appetizer. All you have to do is buy fresh Mushrooms, a stick (1/2 cup) of butter, a package of Hidden Valley Ranch Dressing and some Parmesan Cheese. That is it! You let them cook in the Crock Pot for 4 hours on low and you have a delicious side dish or a great topping for steak.