These French Mashed Potatoes Feel So Sophisticated (but Couldn’t Be Easier)

I’ve been making celery root mashed potatoes for Thanksgiving since I was 14 years old. I got the recipe from a French women’s magazine that my sister sent to me from her year abroad at the Sorbonne. As a young Francophile studying French, that magazine was a worldly treasure. I pored over every page, obsessing over details like how Parisian women tied their silk scarves — and how they cooked chic recipes.

Enter: the recipe for celery root mashed potatoes, which has endured for decades in my family. They strike a sophisticated, continental note among all the other (rather heavy) dishes on our Thanksgiving table. A guest once remarked that they loved the “green taste” of our mashers, and somehow the name stuck — we’ve been calling them “green potatoes” ever since. In all honesty, though, I’d describe the flavor of the celery root in the dish as slightly sweet and earthy, not green. A bit like parsley stems, but more buttery.

If you’re unfamiliar, celery root is a knobby root vegetable that looks something like a dirty softball with roots sprouting out the base. They appear from fall to early spring in well- stocked grocery stores and farmers markets, with the freshest specimens sporting a few puny celery-like stalks still attached to the top. Choose a root that has no mushy spots and is heavy for its size. Once you’ve trimmed the gnarliest roots off the celery root, peel the rest of the thin skin with a vegetable peeler to keep waste to a minimum. 

Because celery root is denser than potatoes, I cut them into thin matchsticks about 1/4- to 1/2-inch thick while keeping the potatoes in rather large (3-inch) chunks or quarters so everything cooks evenly. A bay leaf and garlic cloves are added to the cooking water with a good amount of salt to season the cooking liquid, some of which you’ll reserve and use later to loosen the mash in lieu of milk or cream.

I used to run the cooked veg through a food mill as the French magazine instructed, but these days I prefer them with a bit more texture, so I mash them with a good ol’ potato masher. Then I stir in the reserved cooking liquid, just a few tablespoons at a time, until the mixture is loose and silky. To amplify the flavor of the celery root, the recipe is finished with freshly grated nutmeg and a few pinches of cayenne pepper, a classic French combo that is used to finish cream sauces and gratins. This little detail makes the mash taste trés chic, so don’t skip it!

The finished dish can be made up to a few days in advance and refrigerated, which makes it a real boon when I’m wrestling a turkey or roast and multiple side dishes, plus entertaining guests. To reheat, I scoop them into a small (4- to 5-quart) slow cooker (I rub the crock with butter first) and cook them on low heat until they’re hot in the middle, 3 to 4 hours. They can be held on “keep warm” for an hour or two, if you can wait that long.