Peel and quarter potatoes. Cover with warm water and boil until tender (about 30 minutes). Drain really well. Mash the potatoes with a potato masher or press them through a potato ricer.
Add cream cheese, sour cream, ¼ cup of milk or cream, garlic powder, onion powder, salt and pepper. Beat until light and fluffy. Gradually add more milk or cream, as necessary, to reach the desired consistency. You may not need the full ½ cup, or you might need more than that -- it will depend on the moisture in your potatoes.
Serve immediately with butter on top, or transfer potatoes to a baking dish that has been sprayed with cooking spray. Cover and refrigerate for up to 48 hours.
To reheat: dot with butter and bake, uncovered, for about 30 minutes at 350 degrees F (or until heated through).
Notes
I used white potatoes for this recipe, but you can also use russet potatoes or Yukon Gold potatoes. Red potatoes will work, but they're not my top choice because they tend to yield a less-creamy dish.
Make sure that your cream cheese, sour cream and milk or cream are at room temperature before you mix them into the potatoes.
Use chive cream cheese for extra flavor in the mashed potatoes!
Garnish with chopped fresh chives, green onions, or parsley for a bright, fresh finish to the dish!