1. Place potatoes into a large pot filled with salted water and bring to a boil. Reduce heat to medium-low and simmer until tender, about 20 minutes. Drain.

2. Preheat oven to 400 degrees. Mash peeled potatoes in a large bowl with a potato masher until smooth. Lightly fold in cream cheese and 3 tbsps. of the butter. Stir in the buttermilk until just fluffy, but do not overmix. Add chopped chives. Salt and pepper to taste.

3. Spoon mashed potato mixture into a lightly greased, 10-inch cast iron skillet or a three-quart baking dish. Dot top of potatoes with remaining tablespoon of butter and cover with aluminum foil.

4. Bake, covered, for 30 minutes. Uncover and bake 15-20 more minutes or until thoroughly heated. Sprinkle with additional chives before serving.