Cheesy Root Vegetable Gratin (Perfect Thanksgiving Side Dish)

Creamy, cheesy, and bubbling with golden goodness, this Cheesy Root Vegetable Gratin is a Thanksgiving side dish that steals the spotlight. Tender vegetables melt into rich Gruyère and Parmesan layers, making every bite irresistible. With its crisp top and cozy flavor, it’s the ultimate comfort food for holiday tables and family gatherings.

What is Cheesy Root Vegetable Gratin?

Cheesy Root Vegetable Gratin is a layered casserole-style dish that combines thinly sliced root vegetables baked in a rich cream sauce with melted cheese on top. The vegetables become tender and creamy as they bake, while the top turns beautifully golden and crisp. Unlike plain potato gratin, this version includes a mix of potatoes, parsnips, carrots, celery root, and rutabaga, which adds earthy depth and natural sweetness.

The sauce is made from cream, milk, Dijon mustard, fresh thyme, and rosemary. As the dish bakes, the flavors infuse the vegetables, creating a fragrant and savory base. Gruyère cheese brings a nutty, melty quality, while Parmesan sharpens the overall flavor. Together, they form that irresistible crust everyone fights over.

This gratin is versatile and festive, making it perfect for Thanksgiving. It pairs wonderfully with turkey, roasted meats, or other holiday sides. You can prepare it ahead, bake it just before serving, and trust that it will impress guests with its flavors and comforting texture.

Why You’ll Love This Recipe

You’ll love Cheesy Root Vegetable Gratin because it’s hearty, creamy, and guaranteed to satisfy. The vegetables bake into tender perfection, while the cheesy top delivers crunch in every forkful. It’s not just beautiful to serve, it’s practical too. You can prep it a day ahead and simply bake it before dinner.

This dish feels cozy and indulgent but uses everyday ingredients. The balance of earthy roots, creamy sauce, and melted cheese makes it both rustic and elegant. It’s a recipe that’s crowd-pleasing and family-friendly, so it works for big holiday gatherings and quiet Sunday dinners alike.

Ingredients You’ll Need

Root vegetables explained

This recipe uses a medley of Yukon gold potatoes, parsnips, carrots, celery root, and rutabaga. The mix adds layers of flavor and texture. Potatoes keep it creamy, parsnips add sweetness, carrots bring color, and celery root plus rutabaga offer earthy, slightly peppery notes. Sliced thin, they bake evenly and soften beautifully.

Cream, herbs, and seasoning

The base sauce combines heavy cream, whole milk, Dijon mustard, thyme, and rosemary. Together, they create a fragrant mixture that soaks into the vegetables as they bake. Don’t skip seasoning with salt and pepper between layers. It ensures every bite is flavorful from top to bottom.

The cheeses that make it irresistible

Gruyère cheese provides melty richness with a nutty taste, while Parmesan sharpens the flavor and crisps as it bakes. You can swap Gruyère with cheddar if you prefer a sharper punch. Both cheeses together create the golden, bubbling top everyone loves.

Step-by-Step: How to Make Cheesy Root Vegetable Gratin

Prepare the baking dish

Start by heating your oven to 375°F. Grease a 3-quart baking dish with butter, then rub the bottom and sides with a cut garlic clove for subtle flavor. This little step makes a big difference in taste.

Make the cream and herb mixture

In a medium saucepan, add the cream, milk, Dijon mustard, thyme, rosemary, salt, and black pepper. Bring it just to a simmer, stirring gently. The heat helps release the herb flavors, turning the sauce into a fragrant base for your vegetables.

Slice and layer the vegetables

Peel and thinly slice your potatoes, parsnips, carrots, celery root, and rutabaga. A mandoline works best for even slices, but a sharp knife also does the job. Start layering the vegetables in the dish, overlapping slightly, and sprinkle each layer with salt and pepper before moving to the next. This ensures the seasoning runs throughout the gratin.

Add the cheese topping

Once all vegetables are layered, pour the hot cream mixture evenly over the dish. The liquid should nearly cover the vegetables. Sprinkle the Gruyère and Parmesan evenly on top, making sure the entire surface is coated with cheese.

Bake until golden and bubbly

Cover the dish tightly with foil and bake for 45 minutes. Then remove the foil and bake for another 25 to 30 minutes. The vegetables will be fork-tender, and the top will turn golden brown and bubbly. Let the gratin cool for about 10 minutes before serving so it sets slightly, making it easier to slice and serve.

Recipe Tips for Success

Slice your vegetables as thinly and evenly as possible for uniform cooking. A mandoline ensures consistency. Season each layer lightly with salt and pepper so the whole dish tastes balanced. Don’t rush the cooling step; letting the gratin rest keeps the creamy layers intact. For the best cheese pull, shred Gruyère fresh from a block rather than using pre-shredded cheese.

Make Ahead and Storage Instructions

You can assemble Cheesy Root Vegetable Gratin a day ahead. Cover the unbaked dish tightly with foil and refrigerate it. Bake it straight from the fridge, adding 10–15 minutes to the cooking time. Leftovers keep in the refrigerator for up to 3 days. To reheat, cover with foil and warm in the oven at 350°F until hot. Avoid microwaving if possible, as it can make the vegetables soggy.

Variations and Substitutions

Switch up the vegetables by using turnips, sweet potatoes, or even beets for a colorful twist. If you prefer a sharper flavor, replace Gruyère with aged cheddar. For a lighter version, substitute half-and-half for the cream or add a splash of vegetable broth. Fresh sage or tarragon can also replace rosemary and thyme for a new herbal note.

What to Serve with Root Vegetable Gratin

Cheesy Root Vegetable Gratin pairs perfectly with roasted turkey, glazed ham, or roast beef. For a full Thanksgiving spread, try it alongside Cheesy Scalloped Potatoes for the Holidays, Garlic Mashed Potatoes Recipe for Thanksgiving, or a Southern Green Bean Casserole Classic Side Dish. It also complements lighter sides like Balsamic Glazed Brussels Sprouts Dinner Side, Thanksgiving Glazed Carrots Easy Side Dish, or Bacon Brussels Sprouts for a Festive Dinner. The creamy, rich gratin balances crisp or sweet sides beautifully.

Related Recipes to try

• Cheesy Scalloped Potatoes for the Holidays
• Garlic Mashed Potatoes Recipe for Thanksgiving
• Southern Green Bean Casserole Classic Side Dish
• Balsamic Glazed Brussels Sprouts Dinner Side
• Thanksgiving Glazed Carrots Easy Side Dish
• Bacon Brussels Sprouts for a Festive Dinner

Conclusion

Cheesy Root Vegetable Gratin is creamy, flavorful, and guaranteed to be a holiday favorite. The golden top, tender vegetables, and savory cheese make it a standout side dish. Best of all, you can prep it ahead and serve it effortlessly during Thanksgiving dinner. For more inspiration, check out my recipe collection on Pinterest.

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