Cook potatoes in a pot of salted, boiling water until tender, about 15-20 minutes.
Drain and return the potatoes to the pot and mash with a potato masher.
In a small saucepan, bring butter and milk to a simmer and cook on low until butter is melted.
Add mixture to potatoes and stir to combine. If necessary, mash potatoes further for smooth consistency. Optional: For a smoother consistency, place boiled potatoes in a stand mixer or use a hand mixer to whip until smooth.
Add yogurt, salt, and pepper, and stir until fully incorporated.
Transfer the potatoes to a serving bowl, and garnish with chives.