1Place potatoes in a large saucepan; cover with water. Bring to a boil. Reduce heat; cover and simmer for 15-20 minutes or until potatoes are tender.
2Meanwhile, in a small saucepan, heat milk over low heat until bubbles form around edge. Remove from the heat. Whisk in onion soup mix until dissolved. Set aside.
3Drain Potatoes; transfer to a large bowl. Add the sour cream, chives, cream cheese, pepper and milk mixture; mash until smooth.