(1 ounce) hidden valley dry ranch dressing mix (start with 1/2 package adding in more to taste)
milk (optional and as needed for extra creaminess, or use whipping cream) (optional)
Cook the potatoes in boiling water until fork-tender; drain and place in a large bowl.
To hot potatoes add in cubed butter, cream cheese, sour cream and 1/2 package dry dressing mix; at low speed using an electric mixer beat until until the potatoes are semi chunky (low speed only to start as the potatoes are hot).
Continue beating at HIGH speed until the potatoes are smooth and very fluffy.
At this point do a taste-test if you desire a more stronger ranch flavor then add in more dry dressing mix until desired flavor is achieved, you may also add in milk or whipping cream for a more creamy taste (start with a small amount and add in more).
TO MAKE AHEAD; spread the potato mixture into a greased 13 x 9-inch pan and refrigerate up to 1 day, remove from fridge about 1 hour before baking, then set oven to 350°F and bake uncovered for 30 minutes or until hot.