Cheesy Root Vegetable Gratin – A Creamy & Colorful Showstopper!

This cheesy root vegetable gratin is a stunning and delicious side dish, featuring thinly sliced root vegetables baked in a creamy, savory sauce and topped with melted cheese. The vibrant layers of sweet potatoes, parsnips, and beets make it a true showstopper for any meal, especially during the holidays.​

Why make this recipe

This gratin is as beautiful as it is tasty, offering a more colorful and flavorful alternative to a classic potato gratin. It combines the earthy sweetness of various root vegetables with the rich creaminess of cheese and cream, creating a comforting and impressive side dish that will wow your guests.​

How to make Cheesy Root Vegetable Gratin

The process involves slicing sweet potatoes, parsnips, and beets into very thin rounds, for which a mandoline is highly recommended. Each vegetable is tossed in separate bowls with heavy cream, Parmesan cheese, and thyme. The coated slices are then arranged in alternating, overlapping rows in a greased baking dish, covered, and baked until tender. Finally, the gratin is topped with Gruyère cheese and baked again until the cheese is melted and golden brown.​

Ingredients

• 1 tablespoon unsalted butter, softened​
• 1-2 long sweet potatoes, peeled​
• 3-4 large parsnips, peeled​
• 3-5 small beets, peeled​
• 14 tablespoons heavy cream, divided​
• 4 ounces grated Parmesan cheese, divided​
• 1 ounce shredded Gruyère cheese​
• 1 tablespoon fresh minced thyme, plus more for garnish​
• 1 garlic clove, minced​
• Salt and pepper to taste​

Directions

1. Preheat your oven to 400°F (200°C) and grease a 3-quart baking dish with butter.​
2. Using a mandoline, slice the sweet potatoes, parsnips, and beets into very thin rounds. Keep each vegetable in a separate bowl.​
3. Pour 4 tablespoons of cream over the sweet potatoes and parsnips, and 2 tablespoons over the beets. Add some Parmesan and minced thyme to each bowl, season with salt and pepper, and toss to coat the slices well.​
4. Pour the remaining cream into the baking dish and sprinkle with garlic and some Parmesan cheese.​
5. Arrange the vegetable slices standing up in the dish, creating alternating rows of sweet potato, parsnip, and beet.​
6. Season the top with salt, pepper, and the remaining Parmesan cheese.​
7. Cover the dish with foil and bake for 30 minutes, or until the vegetables begin to soften.​
8. Remove the foil, sprinkle the shredded Gruyère cheese over the top, and bake uncovered for another 18-20 minutes until the vegetables are fork-tender and the cheese is melted and lightly browned.​
9. Garnish with fresh thyme leaves before serving.​

How to serve

Serve the cheesy root vegetable gratin warm as a side dish. It pairs wonderfully with roasted meats like chicken, beef, or pork, and is an excellent addition to a Thanksgiving or Christmas dinner menu.​

How to store

Leftover gratin can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, place it in an oven at 350°F until warmed through.

Tips to make

• Use a mandoline: For uniform, paper-thin slices that cook evenly, a mandoline slicer is the best tool.​
• Keep vegetables separate: Tossing the vegetables in separate bowls prevents the beets from staining the other vegetables, maintaining the colorful layered look.​
• Golden-brown top: For an extra crispy and golden top, you can place the gratin under the broiler for the last few minutes of cooking, watching it carefully to prevent burning.​

Variation

• Different Vegetables: You can use other root vegetables such as potatoes, carrots, or celery root.​
• Cheese Selection: Feel free to experiment with different cheeses. Gorgonzola can add a sharp, tangy flavor, while a mix of cheddar and Parmesan is also a delicious option.​​
• Herbs: You can add other fresh herbs like rosemary or sage along with the thyme for a more complex flavor profile.​

FAQs

What is the best way to slice the vegetables?
Using a mandoline is highly recommended to achieve consistently thin slices, which ensures the vegetables cook evenly and have a delicate texture.​

Can I make this gratin ahead of time?
Yes, you can assemble the gratin a day in advance, cover it, and refrigerate. You may need to add 10-15 minutes to the initial covered baking time when cooking it from cold.

Can I use milk instead of heavy cream?
You can use whole milk as a substitute, but the sauce will not be as thick, rich, or creamy as it would be with heavy cream.​

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