Preheat oven to 350. Place potatoes in a pot with enough water to cover it by 2 inches or so. Bring to a boil and cook until they are tender. Drain and return to pot.
Mash the potatoes and then add the cream cheese, butter, and sour cream. Stir until well combined.
Add chives, 2 cups cheddar cheese, half the bacon, salt, and pepper. Stir.
Transfer to a baking dish and top with remaining cheese.