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Cheesy Root Vegetable Gratin Recipe

4.6 from 82 reviews

This Cheesy Root Vegetable Gratin is a creamy, comforting side dish featuring a mix of thinly sliced root vegetables baked in a rich cheese sauce. Layers of potatoes, sweet potatoes, parsnips, and carrots are enveloped in a velvety cheddar and Parmesan cheese sauce, then baked until tender and topped with a golden, bubbly crust. Ideal for holiday dinners or cozy meals, it combines the natural sweetness of root vegetables with savory, cheesy goodness.

Ingredients

Scale

Vegetables

  • 2 pounds (about 900g) mixed root vegetables (potatoes, sweet potatoes, parsnips, carrots), peeled and thinly sliced
  • 1 small onion, thinly sliced
  • 2 cloves garlic, minced

Cheese Sauce

  • 2 tablespoons butter
  • 2 tablespoons all-purpose flour
  • 2 cups milk (whole or 2%)
  • 1 1/2 cups shredded sharp cheddar cheese, divided
  • 1/2 cup grated Parmesan cheese, divided
  • Salt and black pepper to taste
  • 1/4 teaspoon ground nutmeg (optional)

Garnish

  • Fresh thyme leaves (optional)

Instructions

  1. Preheat the Oven: Preheat your oven to 375°F (190°C). Grease a 9×13 inch baking dish with butter or cooking spray to prevent sticking.
  2. Prepare the Root Vegetables: Peel and thinly slice the mixed root vegetables using a knife or mandoline slicer for even thickness. Place the sliced vegetables in a large bowl.
  3. Sauté the Onion and Garlic: In a medium saucepan, melt 2 tablespoons of butter over medium heat. Add the thinly sliced onion and minced garlic, sautéing for 3-4 minutes until the onion is translucent and fragrant.
  4. Create the Cheese Sauce: Sprinkle the flour over the sautéed onion and garlic and stir constantly for 1-2 minutes to form a roux. Gradually pour in the milk while stirring continuously. Cook the mixture for 5-7 minutes until it thickens. Reduce heat to low and stir in 1 cup shredded cheddar and 1/4 cup grated Parmesan until melted and smooth. Season the sauce with salt, black pepper, and optional nutmeg, adjusting to taste.
  5. Assemble the Gratin: Pour the cheese sauce over the sliced root vegetables in the bowl, gently tossing to evenly coat all pieces.
  6. Layer in the Baking Dish: Transfer the coated vegetables into the prepared baking dish, arranging them evenly in a single layer.
  7. Bake Covered: Cover the dish tightly with aluminum foil and bake in the preheated oven for 35-40 minutes, or until the vegetables are tender when pierced with a fork.
  8. Add the Cheesy Topping: Remove the foil, then sprinkle the remaining 1/2 cup shredded cheddar cheese and 1/4 cup grated Parmesan evenly over the top of the gratin.
  9. Brown and Garnish: Return the uncovered dish to the oven and bake an additional 15-20 minutes until the top is golden brown and bubbly. Optionally, garnish with fresh thyme leaves for a vibrant touch.
  10. Serve and Enjoy: Allow the gratin to cool for a few minutes before serving. Serve warm as a savory, cheesy side dish that complements any special meal or holiday feast.

Notes

  • Use a mandoline slicer for uniform vegetable slices to ensure even cooking.
  • Feel free to substitute any root vegetables or add favorites like turnips or rutabaga.
  • The nutmeg is optional but adds a subtle warm flavor to the cheese sauce.
  • For a richer sauce, use whole milk; for lighter, use 2% milk.
  • This dish can be prepared a day ahead and baked before serving.
  • Leftovers refrigerate well and reheat in the oven for best texture.

Keywords: root vegetable gratin, cheesy gratin, baked root vegetables, holiday side dish, comfort food