Bring butter, sour cream and cream cheese to room temperature.
Wash potatoes, removing any dark or rough spots. In a large pot of salted water, boil potatoes until fork tender. Drain potatoes and return to pot.
Add butter, sour cream, cream cheese and seasonings. Mash potatoes, using a potato masher or hand mixer. Add warmed milk, until desired consistency is reached.
To Freeze I usually serve some of the potatoes immediately and freeze the rest. To freeze, scoop cooled mashed potatoes into quart size freezer bags. If freezing all of the potatoes, you should have enough to fill 6-7 quart size bags. Make sure any excess air has been removed from the bag and that the bag is sealed completely. Freeze until ready to use.
To Serve Mashed potatoes can be thawed in the refrigerator overnight and reheated using various methods, including: on the stove, in the oven, crock pot or microwave. I usually pull a bag of mashed potatoes from the freezer at dinner time and microwave on high 2-3 minutes, then test, and add another minute if necessary. Heating time will vary based on quantity and the wattage of your microwave.
Recipe by About a Mom at https://www.aboutamom.com/make-ahead-freezer-mashed-potatoes/