These potatoes mix in parsnips and garlic for tons of hearty flavor.
In a large pot, cover the parsnips, potatoes, and garlic with a couple of inches of cold water. Bring to a boil over high, season generously with salt , and cook until tender, 20 to 25 minutes.
Meanwhile, in a small pan, heat the milk and butter over low until the milk is warm and the butter melts.
Drain the vegetables. For a smooth mash, pass the vegetables through a food mill. For a more rustic mash, transfer the vegetables to a large bowl and smash with a potato masher. Stir in the milk mixture; season with pepper and the nutmeg.
Transfer to a serving bowl and top with the chives or parsley.