I love bringing this Cheesy Root Vegetable Gratin to the Thanksgiving table, where tender layers of potato, sweet potato, and parsnip bake beneath a golden cheese topping. It feels special enough for a holiday feast, yet the simple prep makes it a comforting side dish for any cool-weather gathering.
Why You’ll Love This Cheesy Root Vegetable Gratin
This gratin combines the earthy sweetness of root vegetables with a creamy garlic and thyme sauce, plus nutty Gruyere and Parmesan on top. The vegetables soften as they bake, while the cheese turns beautifully golden. You can also assemble the dish ahead, then bake it closer to dinner.
Cheesy Root Vegetable Gratin Ingredients & Substitutions
- 1 tablespoon unsalted butter, for greasing the baking dish
- 1 pound Yukon Gold potatoes, peeled and thinly sliced
- 1 pound sweet potatoes, peeled and thinly sliced
- 12 ounces parsnips, peeled and thinly sliced
- 1 1/2 cups heavy cream
- 1 cup whole milk
- 2 garlic cloves, finely minced
- 1 teaspoon fresh thyme leaves, or 1/2 teaspoon dried thyme
- 1/2 teaspoon fine salt
- 1/4 teaspoon black pepper
- Pinch of ground nutmeg
- 1 1/2 cups shredded Gruyere cheese
- 1/2 cup finely grated Parmesan cheese
- 1 tablespoon chopped fresh parsley, optional, for serving
For a slightly different mix, swap some of the parsnips for peeled celery root or turnip. Fontina or sharp white cheddar can stand in for the Gruyere, though the flavor will change a little.
Step-by-Step Instructions to Make Cheesy Root Vegetable Gratin
1. Prepare the baking dish and vegetables
Heat the oven to 375°F (190°C). Butter a 9-by-13-inch baking dish. Slice the potatoes, sweet potatoes, and parsnips into even rounds about 1/8 inch thick so they cook at the same rate.
2. Warm the cream mixture
In a small saucepan, combine the heavy cream, milk, minced garlic, thyme, salt, pepper, and nutmeg. Warm over medium-low heat until steaming, but do not let it boil. Take the pan off the heat.
3. Layer the vegetables
Arrange the sliced vegetables in overlapping layers in the prepared dish, alternating the types as you go. Pour the warm cream mixture evenly over the vegetables. Gently press the top layer down so it is lightly coated.
4. Add cheese and bake
Sprinkle the Gruyere and Parmesan evenly over the top. Cover the dish tightly with foil and bake for 40 minutes. Remove the foil and bake for another 20 to 25 minutes, until the vegetables are tender when pierced with a knife and the top is golden.
5. Rest before serving
Let the gratin rest for 10 to 15 minutes before serving. This gives the creamy layers time to settle and makes it easier to spoon onto plates. Sprinkle with parsley, if you like.
Tips for Success
- Slice the vegetables evenly. A mandoline can help, but use its guard and keep your fingers clear.
- Warm the cream mixture first to help the gratin heat evenly in the oven.
- Cover the dish for the first part of baking so the vegetables soften before the cheese browns.
- Check the center with a thin knife. If the vegetables still feel firm, cover the dish again and bake a little longer.
- Let the gratin rest before serving. The sauce thickens slightly as it cools.
Variations of Cheesy Root Vegetable Gratin
Try a mix of potatoes, sweet potatoes, and celery root, or add a layer of thinly sliced turnip for a more savory note. For extra herbs, add chopped rosemary or sage to the warm cream. You can also replace some of the Gruyere with sharp cheddar for a bolder, familiar cheese flavor.
Serving Suggestions: What to Pair with Cheesy Root Vegetable Gratin
This gratin is right at home beside roast turkey, baked chicken, or a hearty lentil loaf. Add green beans, roasted Brussels sprouts, or a crisp salad to balance its creamy richness. It also pairs well with simple roasted vegetables when you want to keep the meal meat-free.
Storage & Reheating Instructions
Cool leftovers, cover, and refrigerate for up to 4 days. Reheat individual portions in the microwave, or warm the covered baking dish in a 325°F (165°C) oven until heated through. For a crispier top, uncover the dish for the last few minutes. To prepare ahead, assemble the gratin, cover, and refrigerate for up to 24 hours. Add about 10 minutes to the covered baking time if it goes into the oven cold.
Memories Made Around the Table
I like to bring this gratin to the table while it is still warm, with its golden top catching everyone’s eye. At Thanksgiving, it is the kind of side dish that invites a second helping and makes the meal feel a little more welcoming. I often set it beside the other vegetables so everyone can scoop out their favorite mix of tender layers.
FAQs
Can I make Cheesy Root Vegetable Gratin ahead?
Yes. Assemble the dish, cover it, and refrigerate for up to 24 hours before baking. Bake it covered for a little longer if it is still cold from the refrigerator, then uncover it to brown the cheese.
How do I know when the gratin is done?
Slide a thin knife into the center. It should pass through the vegetable layers easily, and the top should be golden. If the vegetables are still firm, continue baking until tender.
Can I freeze leftover gratin?
You can freeze portions in an airtight container for up to 2 months, though the cream sauce may become a little less smooth after thawing. Thaw overnight in the refrigerator and reheat covered in the oven.
Can I use a different cheese?
Yes. Fontina, sharp white cheddar, or a mix of Gruyere and cheddar all work well. Choose a cheese that melts smoothly for the creamiest result.
Final Thoughts
With tender root vegetables, a gently seasoned cream sauce, and a bubbling cheese crust, this gratin makes a cozy addition to a Thanksgiving menu. Prepare it ahead, bake until golden, and let it rest briefly before sharing.
Cheesy Root Vegetable Gratin
Equipment
- 1 9-by-13-inch baking dish
- 1 Small saucepan
- 1 Aluminum foil
- 1 Oven
Ingredients
Ingredients
- 1 tablespoon unsalted butter for greasing the baking dish
- 1 pound Yukon Gold potatoes peeled and thinly sliced
- 1 pound sweet potatoes peeled and thinly sliced
- 12 ounces parsnips peeled and thinly sliced
- 1.5 cups heavy cream
- 1 cup whole milk
- 2 cloves garlic finely minced
- 1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme
- 0.5 teaspoon fine salt
- 0.25 teaspoon black pepper
- 1 pinch ground nutmeg
- 1.5 cups shredded Gruyere cheese
- 0.5 cup finely grated Parmesan cheese
- 1 tablespoon fresh parsley chopped; optional, for serving
Instructions
Instructions
- Heat the oven to 375°F. Butter a 9-by-13-inch baking dish. Slice the potatoes, sweet potatoes, and parsnips into even rounds about 1/8 inch thick.
- In a small saucepan, combine the heavy cream, milk, garlic, thyme, salt, pepper, and nutmeg. Warm over medium-low heat until steaming, but do not let it boil. Remove from the heat.
- Arrange the sliced vegetables in overlapping layers in the prepared dish, alternating the types as you go. Pour the warm cream mixture evenly over the vegetables and gently press the top layer down so it is lightly coated.
- Sprinkle the Gruyere and Parmesan evenly over the top. Cover the dish tightly with foil and bake for 40 minutes. Remove the foil and bake for another 20 to 25 minutes, until the vegetables are tender when pierced with a knife and the top is golden.
- Let the gratin rest for 10 to 15 minutes before serving. Sprinkle with parsley, if desired.