Cheesy Root Vegetable Gratin

This cheesy root vegetable gratin is a warm, comforting dish that layers tender root vegetables with creamy sauce and melted cheese. I love how the sweetness of the sweet potatoes and parsnips balances the earthiness of the beets, all wrapped in a rich, cheesy blanket that feels perfect for a cozy dinner.

Why You’ll Love This Recipe

I like this recipe because it turns simple root vegetables into something elegant and indulgent. The combination of Parmesan and Gruyere makes the dish savory and deeply flavorful. I find that the creamy layers hold the vegetables together beautifully, and the thyme adds a wonderful herbal note that keeps everything bright. It’s a dish I enjoy serving both as a hearty side and as a vegetarian main.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

1 tablespoon unsalted butter softened
1-2 long sweet potatoes (about 2 inches thick), peeled
3-4 large parsnips, ends trimmed and peeled
3-5 small beets, peeled
14 tablespoons heavy cream, divided (whole milk is fine, but mixture won’t thicken as much or be as creamy)
4 ounces grated Parmesan, divided
1 tablespoon fresh minced thyme, divided plus more for garnish
1 garlic clove, minced
1 ounce shredded gruyere
salt and pepper to taste

Directions

1. I start by preheating my oven to 375°F (190°C) and greasing a baking dish with softened butter.
2. I slice the sweet potatoes, parsnips, and beets thinly, about 1/8-inch thick, so they cook evenly and layer nicely.
3. I whisk together 12 tablespoons of the heavy cream, half the Parmesan, half the thyme, and the minced garlic. I season with salt and pepper.
4. I layer the vegetables in the dish, alternating slices of sweet potato, parsnip, and beet.
5. After layering, I pour the cream mixture evenly over the vegetables.
6. I top with the remaining Parmesan, Gruyere, and a drizzle of the last 2 tablespoons of cream.
7. I cover with foil and bake for about 35 minutes. Then I uncover and bake another 20–25 minutes, until the top is golden and bubbly and the vegetables are fork-tender.
8. I let it rest for about 10 minutes before serving, garnished with fresh thyme.

Servings and Timing

This recipe serves 6 people as a side dish. The total time is about 1 hour 15 minutes, with 15 minutes of prep and 60 minutes of baking and resting.

Variations

I sometimes swap the Gruyere for sharp cheddar or fontina for a different flavor. If I want a lighter version, I use half cream and half milk. I also like adding thinly sliced carrots or turnips to the layers. For a stronger herbal note, I mix in rosemary or sage instead of thyme.

Storage/Reheating

I store leftovers in an airtight container in the fridge for up to 4 days. To reheat, I cover the dish with foil and warm it in a 350°F oven until heated through, usually about 20 minutes. Individual portions reheat well in the microwave, though I prefer the oven to keep the top crispy.

FAQs

Can I make this gratin ahead of time?

Yes, I often assemble it a day ahead and refrigerate before baking. I just add 10–15 minutes extra baking time when cooking from cold.

Can I freeze cheesy root vegetable gratin?

I don’t recommend freezing because the cream can separate and the vegetables may get watery when thawed.

How thin should I slice the vegetables?

I aim for about 1/8-inch slices. A mandoline makes this really easy and ensures even cooking.

Can I use different cheeses?

Absolutely. I like Gruyere for its melt and flavor, but sharp cheddar, fontina, or even mozzarella work well.

How do I keep the top from burning?

If the cheese browns too quickly, I loosely cover the dish with foil for the last part of baking.

What can I serve with this dish?

I like pairing it with roasted chicken, grilled steak, or a crisp green salad for balance.

Can I make it dairy-free?

Yes, I can use coconut cream or a dairy-free substitute along with vegan cheese, though the flavor will be slightly different.

Why is my gratin watery?

This usually happens if the vegetables weren’t sliced thin enough or if too much liquid was used. I stick to heavy cream for the best consistency.

Can I add breadcrumbs on top?

Yes, I sometimes mix breadcrumbs with Parmesan for a crunchy topping.

Do I need to pre-cook the vegetables?

No, I don’t pre-cook them. Thin slices bake fully in the oven and keep the dish from getting mushy.

Conclusion

This cheesy root vegetable gratin is a cozy, flavorful dish that transforms humble vegetables into a rich, satisfying meal. I love making it when I want something comforting yet impressive, and the leftovers are just as delicious the next day. It’s one of those recipes I keep coming back to all season long.

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