Parsley Root and Butternut Squash Gratin

Preparation info

  • Difficulty


  • Serves

    6 to 8

Appears in

On dreary rainy weekends during the fall and winter, I stay indoors and putter in the kitchen. I want the oven on for additional warmth, and I often get hungry for a crusty Parmesan-topped vegetable gratin. This humble dish, with multiple layers of potato, butternut squash, and parsley root, is scented with garden herbs—whatever mixture pleases you—and baked with just enough cream and Parmesan to add richness. The parsley root adds a subtle, rustic earthiness to the gratin. I prefer to buy a small butternut squash, but it’s sometimes hard to find one. You’ll most likely end up with a bigger squash than you need for this gratin. Use the top portion that does not contain the seeds for this dish, and cube the remainder for a quick sauté on another night.


  • 4 tbsp/60 ml. extra-virgin olive oil
  • 1 large yellow onion, 10 oz/280 g, thinly sliced
  • Kosher or fine sea salt
  • Freshly ground pepper
  • 2 tbsp. minced mixed fresh herbs such as rosemary, thyme, sage, and parsley
  • 12 oz/340 g Yukon Gold potatoes, peeled and cut into slices 1/16 in/2 mm thick
  • One 12-oz/340-g butternut squash, trimmed, halved lengthwise, seeded, peeled, and cut into slices 1/16 in/2 mm thick
  • 3 tbsp. heavy whipping cream
  • ½ cup/55 g freshly grated Parmesan cheese, preferably Parmigiano-Reggiano
  • 12 oz/340 g parsley root, trimmed, peeled, and cut into slices 1/16 in/2 mm thick
  • Âľ cup/45 g lightly packed fresh bread crumbs (see Cook’s Note)
  • 1 large garlic clove, minced


  1. Position a rack in the center of the oven and preheat to 350°F/180°C/gas 4. Grease a 2-qt/2-L shallow, broiler-safe baking or gratin dish with ½ tbsp. of the oil.
  2. In a large sauté pan, heat 1½ tbsp. of the oil over medium-high heat. Add the onion, season with salt and pepper, and sauté until translucent, about 4 minutes. Add the herbs and toss to combine. Remove the pan from the heat.
  3. Arrange half of the potato slices in a tight, overlapping layer on the bottom of the prepared baking dish. Sprinkle lightly with salt and pepper. Spread half of the sautéed onions evenly over the top. Arrange half of the squash slices on top of the onions in a tight, overlapping layer. Sprinkle lightly with salt and pepper. Drizzle 1½ tbsp. of the cream over the squash and scatter 1 tbsp. of the Parmesan over the top. Next, arrange half of the parsley root in an even layer on top and season with salt and pepper. Repeat the layers exactly as you have just done, using all of the remaining vegetables and cream and 1 tbsp. of the cheese.
  4. Cover the dish tightly with aluminum foil. Bake until the squash and potatoes are tender when poked with a fork, 35 to 45 minutes.
  5. Meanwhile, heat the remaining 2 tbsp. oil in a small sauté pan over medium heat. Add the bread crumbs and garlic and stir to toast lightly, about 3 minutes. Remove from the heat and transfer to a shallow bowl to cool for 10 minutes. Add the remaining 6 tbsp/40 g Parmesan cheese to the bread crumbs and toss to combine.
  6. Remove the gratin from the oven, uncover, and sprinkle the bread crumb mixture evenly over the top. Position an oven rack about 4 in/10 cm. from the broiler and turn the oven setting to broil. Place the gratin under the broiler to crisp and brown the top, 3 to 5 minutes. Set aside to rest for 10 minutes before serving. Cut into wedges or squares and serve directly from the baking dish.