If using a block of cream cheese, cut into 10 - 12 squares and leave at room temperature for an hour. Fry bacon over medium heat until cooked, but not crispy or burned. Blot with a paper towel and dice. Grate cheese and finely dice chives.
Whisk/beat cream cheese, mayonnaise and sour cream until smooth (or almost smooth). Fold in bacon, grated cheese and chives. Place in oven proof baking dish. At this point, dip can be covered and refrigerated until ready to bake.