Rach cooks potatoes, parsnips and garlic all at once for ease—her trick? Cut the parsnips smaller than the potatoes so they take the same amount of time to cook!
For a complete holiday feast, check out Rach's Hard Cider-Braised Pork Shoulder, Cran-Apple Sauce, and Green Beans With Shallots.
In a large pot, cover the parsnips, potatoes and garlic with a couple 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 salt, pepper and nutmeg.
Transfer to a serving bowl and top with chives or parsley.