Fennel, Carrot, and Leek Gratin

published Oct 29, 2021
Fennel, Carrot, and Leek Gratin Recipe

Fennel, carrots, and leek are mixed with an aromatic Parmesan cream sauce and topped with pecan breadcrumbs for the ultimate veggie gratin.


Prep30 minutes to 35 minutes

Cook50 minutes to 55 minutes

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Carrot and fennel gratin
Credit: Photo: Jenny Bravo | Food Stylist: Catrine Kelty

This recipe celebrates one of my all time favorite vegetables, fennel. I love fennel in every form — braised, shaved, caramelized, you name it — but my favorite way is deeply roasted and tender. This recipe is the ultimate iteration: fennel is mixed with aromatics like leeks and fresh thyme, then tossed into a cream sauce, topped with breadcrumbs, and baked until golden for the tastiest gratin. It’s easy enough to enjoy as an any day side, but elegant enough for your holiday table.

Credit: Photo: Jenny Bravo | Food Stylist: Catrine Kelty

3 Tips for the Best Fennel and Carrot Gratin

  1. Thinly slice the vegetables. You’ll want to start by thinly slicing the fennel, carrots, and leek. I like to use a mandoline for this, but a sharp knife will work, too! Thin slices ensure they bake up nice and tender.
  2. Uncover for the last 20 minutes of baking. This ensures the veggies on top get nicely browned and caramelized and the savory breadcrumb topping gets toasty.
  3. Speaking of the topping, don’t skip it. This is far from your average breadcrumb topping. You’ll mix pecans, breadcrumbs, and thyme with garlic butter, then sprinkle it all over the gratin before baking. Don’t have pecans? Try walnuts instead.

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Fennel, Carrot, and Leek Gratin Recipe

Fennel, carrots, and leek are mixed with an aromatic Parmesan cream sauce and topped with pecan breadcrumbs for the ultimate veggie gratin.

Prep time 30 minutes to 35 minutes

Cook time 50 minutes to 55 minutes

Serves 8

Nutritional Info


  • 1 1/2 pounds

    fennel bulbs (about 2 large)

  • 1 pound

    medium carrots (5 or 6)

  • 1

    large leek (about 8 ounces)

  • 2 cloves

    garlic, divided

  • 1 small bunch

    fresh thyme (about 12 sprigs)

  • 3 ounces

    Parmesan cheese, divided, plus more for topping

  • 1 1/2 cups

    heavy cream

  • 6 tablespoons

    unsalted butter, divided

  • 3 teaspoons

    kosher salt, divided

  • 1/2 teaspoon

    freshly ground black pepper, divided

  • 1/2 teaspoon

    grated nutmeg

  • 1/4 teaspoon

    red pepper flakes

  • 1 1/2 cups


  • 1 1/2 cups

    fresh sourdough breadcrumbs


  1. Arrange a rack in the upper third of the oven and heat the oven to 400ºF.

  2. Prepare the following, adding each to the same extra-large bowl or extra-large pot as you complete it: Trim the fronds from 1 1/2 pounds fennel. Halve the bulbs lengthwise through the root. If the bulbs are large, halve each piece again. Thinly slice the fennel about 1/4-inch thick (about 4 cups). Peel and thinly slice 1 pound carrots on a slight diagonal (about 2 1/2 cups). Halve 1 large leek lengthwise and rinse between the layers to clean. Thinly slice the white and light green parts crosswise.

  3. Thinly slice 1 garlic clove and add it to the bowl; finely grate 1 garlic clove and reserve for the topping. Pick the leaves from 1 bunch fresh thyme until you have 2 tablespoons; add 1 tablespoon to the bowl and place the remaining 1 tablespoon in a medium bowl. Finely grate 3 ounces Parmesan cheese (about 1 1/2 cups); add 1 cup to the bowl and gently toss until combined; reserve the remaining cheese for the topping.

  4. Place 1 1/2 cups heavy cream, 4 tablespoons of the unsalted butter, 2 teaspoons of the kosher salt, 1/4 teaspoon of the black pepper, 1/2 teaspoon grated nutmeg, and 1/4 teaspoon red pepper flakes in a small saucepan over low heat. Cook, stirring, until the butter just melts, about 5 minutes.

  5. Pour the cream mixture over the fennel mixture and stir until the vegetables are coated. Transfer to a 9x13-inch or 3-quart baking dish and spread into an even layer. Cover the baking dish with aluminum foil. Bake for 20 minutes. Uncover and continue to bake until the fennel is tender and the top is beginning to darken, 25 to 30 minutes more. Meanwhile, prepare the topping.

  6. Coarsely chop 1 1/2 cups pecans and add it to the bowl with the thyme. Add 1 1/2 cups fresh sourdough breadcrumbs, the remaining 1 teaspoon kosher salt, and 1/4 teaspoon black pepper. Melt the remaining 2 tablespoons unsalted butter in the microwave or on the stovetop. Add the reserved grated garlic to the butter and stir to combine. Pour the garlic butter over the breadcrumb mixture and toss until evenly coated.

  7. Sprinkle half the remaining cheese on the gratin. Sprinkle all of the topping over the cheese, then sprinkle with the remaining cheese. Bake until the topping is deep golden-brown, 12 to 15 minutes more. Let rest 10 minutes before serving.

Recipe Notes

Storage: Leftovers can be refrigerated in an airtight container for up to 4 days.