Root Veggie Gratin | Recipeish | Gustus Vitae

  • Yield: Serves 5-8.
  • Time Estimate: 3 hours, including 1:40 unattended.
  • Storage Notes: Will keep for 3 days covered and refrigerated.
  • Difficulty: Medium - mandolins can be dangerous.

Hearty root veggies are one of the perks of colder weather, and we love this recipe for all sorts of reasons: it presents beautifully, its lovely either as a main or the side for a roast, keeps well, and uses a whole bunch of fall and winter favorites: big carrots, parsnips, and white and orange sweet potatoes.

Using a mandolin and keeping the veggies uniform and super thin ensures even cooking, but even more importantly, you can get a bit of everything in each bite. Take your time setting up this dish - it's worth it!


    • Preheat oven to 350F, and remove butter from the fridge.
    • Rinse and peel all veggies: carrots, white and orange sweet potatoes, and parsnips, before removing both tops and bottoms.
    • Carefully, using a mandolin, thinly slice the top 2/3rds of parsnips and carrots - you're looking for them to be both quite large and of uniform width, and reserve, separately.
    • Depending on the width of the sweet potatoes, divide into halves or thirds, then again slice and reserve using the mandolin.
    • Arrange veggies in 4 separate large bowls, discarding any slices that are too wide, small, large, etc.
    • In another large mixing bowl, shake in This Thing of Ours, This Thing of Ours Part II: The Truffle Edition, Granulated Garlic, Foragers Favorite, and briefly whisk to combine.
    • Pour over cream, spoon in creme fraiche, and sprinkle in Parmesan cheese.
    • The butter should have softened by now - if not, pop in the microwave for :20 to soften before also adding to mix.
    • Using a whisk or, if needed, a hand mixer, combine all ingredients into a rich sauce. It should have an even, thick consistency with no irregular lumps.
    • Pour 3/4ths of the sauce, in even amounts, over each of the 4 separate bowls of sliced veggies.
    • Working carefully so as to not break the thin slices, thoroughly massage the sauce into the slices, ensuring that each one is coated. You may need to pull apart some of the slices to make sure that each has sauce on it. 
    • Prep a ceramic 9x9 baking dish - we love this one from Emile Henry.
    • Start building your gratin! Working from side to side, and building up, arrange veggies in rows.
    • Make sure to press down firmly, both top to bottom and side, to make sure the rows don't collapse forward, and if they do, just push back firmly.
    • The whole thing needs to be very compressed - try to wedge in as many slices as you possibly can.
    • Once you can't fit any more in, ladle the remaining sauce over the rows, then lay down the fresh rosemary in between.
    • Give everything a final sprinkle with This Thing of Ours, Part II, Garlic, and Forager's Favorite, cover with foil, and pop in the oven for 1:30.
    • After an hour and half, remove foil, and return to oven for 10 minutes to give it a final crisp.
    • Remove and rest for 10-15 minutes, then serve, and devour.
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