Salads & Side dishes

Cheesy Root Vegetable Gratin

By Clara ·
November 1, 2026

When the foil comes off, the cream is bubbling around the edges and the Gruyère has turned golden on top. Underneath, the potatoes, parsnips, and carrots are tender enough to slice through with a knife. That’s the moment I look for with this cheesy root vegetable gratin: the vegetables should feel soft all the way through, not just browned on top.

I warm the cream and milk with garlic and thyme before they go into the dish. That gives the liquid a head start without boiling it, and it spreads more evenly through the overlapping vegetables. Yukon Gold potatoes bring a creamy center, while the carrots and parsnips add their own sweetness. The finished gratin is rich without tasting like one long layer of potato, with a bubbling cheese top and tender, savory slices beneath.

Why the Potatoes Need to Share the Dish With the Parsnips

A gratin made with potatoes alone can feel heavy from the first bite to the last. Carrots and parsnips break up that richness with a little sweetness and a more delicate texture, while the potatoes help give the cream a fuller, more cohesive feel. Each vegetable has a different job, so the balance matters more than making one of them the star.

Mixing the vegetables as you layer them is what makes that balance carry through the dish. If you stack all the potatoes together, then all the carrots, each serving can come out with a very different ratio. Overlapping a mix of rounds lets the cream reach the whole pan and gives each portion a bit of each root vegetable. The slices also need to be even: a thicker piece can stay firm after the thinner rounds are tender, even when the top is bubbling. A consistent cut helps the center cook at the same pace as the edges.

What the Potatoes, Cream, and Gruyère Each Bring

• Yukon Gold potatoes — Their creamy texture suits a baked gratin, and they hold their shape better than very starchy potatoes. If you use russets instead, expect them to soften more and thicken the cream; cut them carefully so the rounds stay even.
• Parsnips and carrots — Parsnips bring a distinct earthy sweetness, and carrots make the mix sweeter and familiar. If you’re short on parsnips, replace them with more carrots; the gratin will be sweeter and less earthy. Peel both well and trim away any tough ends.
• Heavy cream and whole milk — The cream gives the sauce its richness, while milk keeps it from becoming overly heavy. Half-and-half can stand in for the combined dairy, though the finished gratin will be less lush. Warm the mixture gently so the garlic and thyme infuse it without bringing it to a boil.
• Gruyère — This cheese melts into a savory, nutty top. A good block grated at home gives you control over the texture; Swiss cheese is a useful replacement with a milder, less nutty taste. Finely chopped garlic and dried thyme spread their flavor through the warm dairy rather than sitting in one spot.

How to Get Tender Centers Before the Gruyère Turns Golden

Warm the garlic and thyme into the dairy

Set the oven to 375°F and butter a 9×13-inch baking dish. In a saucepan, warm the cream, milk, garlic, thyme, salt, and pepper over medium heat for about 3 to 5 minutes. Stop when the mixture is steaming; it shouldn’t boil. Boiling can make the dairy less smooth, so take it off the heat as soon as you see steady steam.

Slice the roots into even rounds

Peel the potatoes, parsnips, and carrots, then cut them into 1/8-inch-thick rounds. A sharp knife helps keep the slices neat; if some pieces are noticeably thicker, they’ll take longer to become tender. Arrange the rounds in overlapping layers in the buttered dish, mixing the vegetables as you go. Keep the layers loose enough for the warm cream to flow between them.

Pour and add the cheese

Pour the warm cream mixture evenly over the layered vegetables. Aim across the whole surface instead of pouring in one spot, so the garlic and thyme aren’t concentrated in a single area. Sprinkle the grated Gruyère over the top. The cheese will melt into the surface as the vegetables bake.

Bake covered, then brown the top

Cover the dish tightly with foil and bake for 55 to 65 minutes. Check the center with a knife; it should slide easily into the vegetables, not catch on a firm slice. Once the center is tender, uncover the dish and bake for 20 to 25 minutes more, until the top is golden and bubbling. If the middle is still firm, keep it covered until the knife test passes rather than uncovering it early.

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Cheesy Root Vegetable Gratin

Cheesy root vegetable gratin layers Yukon Gold potatoes, parsnips, and carrots in a thyme-scented cream sauce beneath grated Gruyère. It bakes until tender, golden, and bubbling, making a hearty side dish for a holiday table.

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Prep Time 25 minutes mins

Cook Time 1 hour hr 27 minutes mins

Resting 15 minutes mins

Total Time 2 hours hrs 7 minutes mins

Servings: 8 servings

Course: Side Dish

Cuisine: American

Calories: 655

Ingredients Equipment Method Notes

Ingredients

  

• 1 tbsp unsalted butter softened
• 2 cups heavy cream
• 1 cup whole milk
• 2 cloves garlic finely chopped
• 1 tsp dried thyme
• 1.25 tsp kosher salt
• 0.5 tsp black pepper
• 2 lb Yukon Gold potatoes peeled
• 1 lb parsnips peeled
• 1 lb carrots peeled
• 8 oz Gruyère cheese grated

Equipment

• 1 9x13-inch baking dish

Method

 

1. Heat the oven to 375°F and grease a 9x13-inch baking dish with the butter.
2. Warm the heavy cream, milk, garlic, thyme, salt, and pepper in a saucepan over medium heat until steaming, about 3 to 5 minutes; do not let it boil.
3. Slice the potatoes, parsnips, and carrots into 1/8-inch-thick rounds.
4. Arrange the vegetables in overlapping layers in the prepared dish, mixing them as you go.
5. Pour the warm cream mixture evenly over the vegetables and sprinkle the Gruyère over the top.
6. Cover the dish tightly with foil and bake for 55 to 65 minutes, until a knife slides easily into the center.
7. Uncover and bake for 20 to 25 minutes more, until golden and bubbling.
8. Let the gratin rest for 15 minutes before serving.

Notes

For even cooking, slice the vegetables uniformly to 1/8 inch thick. Refrigerate leftovers for 3 to 4 days; freezing is not recommended because the cream sauce may separate. For a lower-lactose version, use lactose-free cream and milk and a suitable aged cheese.