In a large mixing bowl, mash the hot potatoes.
Add the cream cheese in small pieces and then add the butter.
Mix well until cheese and butter are melted and mixed.
Mix in the sour cream.
Add eggs, milk, salt and pepper.
Beat until light and fluffy.
Place in a 9x13 inch dish and refrigerate for several hours or overnight.
Bake at 350 degrees for 45 minutes or until lightly browned on top.
Sprinkle with chives before serving (optional)