Passing starchy boiled potatoes through a food mill (or a potato ricer) results in an impossibly smooth yet still fluffy mash. If you prepare these potatoes in advance (which you almost certainly will), hold off on adding olive oil, which will lose much of its peppery flavor and fragrance as it sits. Reheat the purée in a pot over medium-low heat, adding more butter as needed until they are no longer dry, then add a very good quality extra-virgin olive oil just before serving.
- 8 large Idaho potatoes (3 lb. 12 oz.), scrubbed
- 1 Tbsp. fine sea salt, plus more as needed
- 12 Tbsp. (6 oz.) unsalted butter, cut into pieces
- Freshly ground black pepper
- Freshly grated nutmeg
- ⅓ extra-virgin olive oil (preferably from Provence), plus more for drizzling
- ¼ cup finely chopped chives
- To a large pot over high heat, add the potatoes, sea salt, and enough cold water to cover by 2 inches. Bring to a boil and cook until the potatoes are very tender when poked with a paring knife, 35–40 minutes.
- Drain the potatoes and cool slightly, then use a dry dish towel to rub or peel the skins away. Place a food mill over a large bowl and pass the potatoes through it (or use a potato ricer), adding the butter a little bit at a time as you go. Season to taste with more sea salt, black pepper, and nutmeg. Just before serving, fold in the olive oil, then transfer the potatoes to a serving bowl or platter. Drizzle with additional olive oil, sprinkle with chopped chives, and serve immediately.