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–+ servings
root vegetable gratin in a baking dish and topped with fresh thyme
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The Best Root Vegetable Gratin

This root vegetable gratin is a perfect side dish that brings depth and coziness to any meal, and it’s a showstopper on holiday tables! My version, made with layers of colorful root veggies and an irresistible miso cream sauce, takes this gratin to a comfort food level of deliciousness. Topped with melted cheese and infused with earthy thyme, this gratin is the perfect blend of creamy, savory, and just a hint of warmth.
Prep Time15 minutes
Cook Time45 minutes
Total Time1 hour
Course: Side Dish
Servings: 8
Author: Pamela

Ingredients

  • ¼ cup white miso paste not low-sodium
  • 1 ½ cups heavy cream or rich cashew milk
  • 1 ½ cups vegetable or chicken broth
  • 6 garlic cloves minced
  • 2 Tablespoons fresh thyme leaves or 2 teaspoons dried thyme
  • 1 teaspoon black pepper
  • A big pinch of salt
  • ¼ teaspoon ground nutmeg
  • ¼ cup caramelized onion jam I used Divina or saute 1 onion, diced
  • 4 pounds mixed root vegetables such as potatoes, sweet potatoes, carrots, parsnips, celery root, rutabaga, fennel, etc., sliced ⅛ -inch thick (THIN)
  • 1-2 cups shredded Gruyere or Comte cheese
  • Olive oil
  • Salt to taste

Instructions

  • Preheat your oven to 375°F (190°C).
  • In a saucepan, whisk together the white miso paste, heavy cream, vegetable broth, minced garlic, thyme leaves, black pepper, a pinch of salt, and nutmeg. Heat the mixture over medium heat, stirring until the miso paste is fully dissolved and the ingredients are well combined. Remove the mixture from heat and stir in the onion jam..
  • In a large mixing bowl, combine the thinly sliced root vegetables with the miso cream mixture. Make sure the vegetables are well coated.
  • Grease 13 x 9 baking dish with olive oil. Layer the coated root vegetables in the dish, slightly overlapping the slices. Pour any remaining miso cream mixture over the top of the vegetables.
  • Cover the baking dish with aluminum foil and place on a baking sheet. Bake in the preheated oven for about 45 minutes.
  • Remove the foil and check to make sure the vegetables are tender by poking them with a paring knife. You can pause the recipe here, let it sit at room temp for a couple hours, and finish it after the turkey comes out of the oven. Sprinkle the shredded cheese over the top of the gratin and continue baking for an additional 15-20 minutes or until cheese is melted and lightly browned.
  • Let the gratin cool slightly before serving. Garnish with fresh thyme leaves if desired and season with salt to taste.

Notes

  • Keep the slices thin and uniform. For perfectly even slices, use a mandoline to cut your root vegetables. This ensures uniform thickness, which is key for even cooking and those beautiful, layered visuals that make gratins so irresistible.  If you don’t have a mandoline, a sharp knife will work - just try to get slices about 1/8-inch thick.
  • Use high-quality cheese. The cheese layer really shines here, so try to use Gruyère, Comté, or another high-quality option. The mild nuttiness and melting quality elevate the dish.
  • Let the gratin rest. Allowing the gratin to cool slightly before serving helps the layers set, making it easier to serve and enhancing the flavors.
  • Storage: Let the gratin cool, then cover it tightly or store it in an airtight container. Refrigerate for up to 3 days.
  • To freeze, bake until the vegetables are tender but skip the cheese topping. Cool completely, wrap tightly, and freeze for up to 1 month. To reheat, thaw the frozen gratin overnight in the fridge, top with cheese, and bake at 375°F (190°C) until warmed through and bubbly.