Creamy Mashed Potato Bake

• 3½ pounds russet potatoes, peeled, cut into 1-inch cubes
• 1 8-ounce package cream cheese, room temperature
• ½ cup sour cream
• ½ cup whole milk
• ¾ cup chopped fresh chives (about 3 bunches)
• ½ teaspoon salt
• ½ teaspoon white pepper
• 1 tablespoon chilled butter, cut into small pieces
• ½ cup parmesan cheese

Grease 6- to 8-cup ovenproof baker. Boil potatoes in salted water until tender, 15 minutes. Drain potatoes and mash with cream cheese.  Add sour cream, milk, chives, salt, and pepper.  Transfer potatoes into prepared dish; dot with chilled butter. Sprinkle with parmesan.  (Can be made 2 hours ahead; let stand at room temperature.)

Bake potatoes at 350°F until brown on top, about 35 minutes.