Preheat oven to 350°. Spray an 8x8-inch (or 9x9-inch) baking dish with nonstick cooking spray. Set aside.
To a large pot of cold salted water, add potatoes. (Make sure the water covers the potatoes.) Cover the pot and bring to a boil over high heat.
After the water has come to a boil, uncover and boil over medium-high heat until fork-tender, about 25 minutes. Drain the potatoes and return them to the pot. Remove from heat.
Lightly mash the potatoes. Add the butter, cream, and cream cheese. Mash until creamy.
Add salt, pepper, bacon (reserving about 2 tablespoons for the topping), and ½ cup of cheese. Stir to combine.
Transfer into the prepared baking dish. Top with the remaining ½ cup of cheese and the reserved bacon.
Bake for 10-12 minutes, or until the cheese is hot and bubbling.
Serve warm, garnished with chives and a dollop of sour cream.