Cheesy Root Vegetable Gratin

This Cheesy Root Vegetable Gratin (Sweet Potato, Potato & Parsnip) is the ultimate comfort food side dish, combining earthy root vegetables with a rich, velvety cream sauce and a golden, bubbly cheese topping. It is the perfect centerpiece for holiday dinners, cozy Sunday suppers, or any occasion that calls for a warm and satisfying vegetable bake.

Why You Will Love This Recipe

This gratin is a crowd-pleaser that balances the natural sweetness of sweet potatoes and parsnips with the savory starchiness of Yukon Gold potatoes. The combination of textures creates a sophisticated dish that feels gourmet yet remains incredibly easy to prepare. Whether you are looking for a reliable Thanksgiving side or a hearty vegetarian main course, this dish delivers consistent, delicious results every single time.

Ingredients

• 2 large Yukon Gold potatoes, thinly sliced
• 2 large sweet potatoes, peeled and thinly sliced
• 3 medium parsnips, peeled and thinly sliced
• 2 cups heavy cream or half-and-half
• 3 cloves garlic, minced
• 1 teaspoon fresh thyme leaves
• 1 cup Gruyere cheese, freshly grated
• 1 cup sharp white cheddar, shredded
• 1/4 teaspoon ground nutmeg
• Salt and black pepper to taste
• 2 tablespoons unsalted butter, softened

Step-by-Step Instructions

1. Preheat your oven to 375 degrees Fahrenheit and lightly grease a 9×13 inch baking dish with butter.
2. In a medium saucepan, combine the heavy cream, minced garlic, thyme, nutmeg, salt, and pepper. Heat over medium until the mixture begins to simmer, then remove from heat.
3. Arrange the thinly sliced potatoes, sweet potatoes, and parsnips in the prepared baking dish, alternating them to create an attractive, layered pattern.
4. Pour the seasoned cream mixture evenly over the vegetables, ensuring every slice is coated.
5. Cover the dish tightly with aluminum foil and bake for 30 minutes.
6. Remove the foil, sprinkle the top generously with the Gruyere and white cheddar cheese, and return to the oven uncovered for another 20 to 25 minutes until the vegetables are tender and the cheese is golden and bubbling.
7. Allow the gratin to rest for 10 minutes before serving to ensure the sauce thickens slightly.

Expert Tips / Pro Tips

For the most consistent results, use a mandoline slicer to ensure your vegetable slices are uniform in thickness; this ensures they all cook through at the same rate. Always grate your cheese from a block rather than using pre-shredded bags, as the anti-caking agents in bagged cheese prevent it from melting into a smooth, creamy texture. If you notice the cheese browning too quickly before the vegetables are tender, tent a piece of foil loosely over the top.

Variations & Substitutions

If you prefer a lighter version, you can substitute a portion of the heavy cream with whole milk or vegetable broth. For added flavor, consider layering in thinly sliced leeks or caramelized onions between the vegetable layers. If you want a bit of crunch, top the gratin with a mixture of panko breadcrumbs and melted butter during the final 10 minutes of baking.

Serving Suggestions

This dish pairs beautifully with roasted proteins such as herb-crusted pork tenderloin, roast chicken, or seared steak. To balance the richness of the cheese and cream, serve it alongside a crisp green salad tossed in a sharp vinaigrette or steamed green beans with a hint of lemon zest.

Storage, Freezing & Reheating

Store leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, cover the dish with foil and warm in the oven at 325 degrees Fahrenheit until heated through. While this dish can be frozen, note that the texture of the cream sauce may change slightly; for best results, freeze unbaked, then thaw completely in the refrigerator before baking.

Nutrition Information

FAQ

Can I prepare this dish ahead of time?

Yes, you can assemble the gratin up to 24 hours in advance. Keep it covered in the refrigerator and let it sit at room temperature for 20 minutes before placing it in the oven to bake.

Do I need to peel the vegetables?

Peeling the parsnips and sweet potatoes is recommended for the best texture, as their skins can be tough. Yukon Gold potatoes have thin skins and can be left on if you prefer a more rustic presentation.

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Cheesy Root Vegetable Gratin

A comforting, elegant side dish featuring thinly sliced potatoes, parsnips, and sweet potatoes baked in a rich, garlic-infused Gruyère cream sauce.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 50 minutes mins

Total Time 1 hour hr 10 minutes mins

Servings: 8 servings

Course: Dinner, Side Dish

Cuisine: French, Vegetarian

Calories: 385

Ingredients Method Notes

Ingredients

  

Vegetables

• 1 lb Yukon Gold potatoes peeled and thinly sliced
• 1 lb parsnips peeled and thinly sliced
• 1 lb sweet potatoes peeled and thinly sliced

Cream Sauce & Topping

• 2 cups heavy cream
• 3 cloves garlic minced
• 2 cups Gruyère cheese shredded
• 1 tsp fresh thyme chopped
• 1 tsp kosher salt
• 0.5 tsp black pepper

Method

 

Instructions

1. Preheat your oven to 375°F (190°C) and lightly grease a 9×13 inch baking dish with butter.
2. In a medium bowl, whisk together the heavy cream, minced garlic, fresh thyme, salt, and black pepper.
3. Arrange the thinly sliced potatoes, parsnips, and sweet potatoes in the baking dish, alternating them in overlapping rows for an even distribution.
4. Pour the cream mixture evenly over the vegetables, ensuring it reaches the bottom of the dish.
5. Cover the dish tightly with aluminum foil and bake for 30 minutes.
6. Remove the foil, sprinkle the shredded Gruyère cheese over the top, and bake uncovered for an additional 20 minutes or until the vegetables are tender and the cheese is golden brown and bubbling.
7. Let the gratin rest for 10 minutes before serving to allow the sauce to thicken.

Notes

For best results, use a mandoline slicer to ensure all vegetable slices are uniform in thickness, which allows them to cook at the same rate.