Peel and cut the potatoes in half. Place them in a large saucepan and cover with cold water. Bring to a boil, then reduce to medium heat and cook until a fork slides in easily — about 25 to 30 minutes.
While the potatoes cook, gently heat the milk in a bowl or saucepan. Add the cream cheese and butter, stirring until melted and combined into a smooth mixture. This step ensures the ingredients blend easily into the hot potatoes later.
Once the potatoes are fork-tender, drain them well and let them sit for a minute in the warm pot so extra moisture evaporates. Mash until smooth and fluffy using a masher or ricer.
Pour the warm milk, butter, and cream cheese mixture into the mashed potatoes. Add salt and gently mix until fully incorporated. Be careful not to overmix — that can make the mash gluey instead of creamy.
Transfer to a serving bowl and top with a little butter and chopped chives for garnish. If not serving immediately, cover and keep warm in a low oven or slow cooker until ready to enjoy.