1. Place potatoes in a large saucepan; cover with water. Bring to a boil; reduce heat, and simmer 15 minutes or until tender. Drain. Press potatoes through a ricer back into pan, or mash with a potato masher to desired consistency.
2. Add buttermilk, milk, melted butter, kosher salt, and white pepper to potato mixture; stir well. Top with chopped fresh chives.