Name: Cheesy Root Veggie Gratin
Prep time: 30 min
Cook time: 1 h 10 min
Total time: 1 h 40 min
Cuisine: Comfort Food
Ingredients: 2 large Russet or Yukon Gold potatoes, peeled and thinly sliced; 2 medium sweet potatoes, peeled and thinly sliced; 3 medium carrots, peeled and thinly sliced; 2 medium parsnips, peeled and thinly sliced; 1 small celeriac, peeled and thinly sliced (optional); 1 tablespoon olive oil or melted butter; 1 teaspoon fresh thyme leaves, chopped; 1/2 teaspoon salt; 1/4 teaspoon black pepper; For the sauce:; 4 tablespoons unsalted butter; 4 tablespoons all-purpose flour; 4 cups whole milk, warmed; 1 cup heavy cream, warmed; 2 cloves garlic, minced; 1 small shallot, finely minced (or 1/4 small onion), finely minced; 1/2 teaspoon freshly grated nutmeg; 1 teaspoon salt; 1/2 teaspoon white pepper; 2 cups freshly grated Gruyère cheese, divided; 1 cup freshly grated sharp white cheddar cheese, divided; 1/2 cup freshly grated Parmesan cheese, divided; 1/2 cup panko breadcrumbs (optional); 2 tablespoons melted butter (if using breadcrumbs); Extra fresh thyme sprigs, for garnish

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Cheesy Root Veggie Gratin

There’s something quietly comforting about a dish that smells like autumn and tastes like home — this Cheesy Root Veggie Gratin is exactly that. Layers of potatoes, sweet potatoes, carrots, parsnips and optional celeriac are baked in a rich, nutmeg-scented cheese sauce until golden and bubbling; it’s the kind of recipe that makes you want to set an extra plate. If you like dishes that can stand alone or star alongside roast meats and greens, this one fits perfectly, and it pairs beautifully with lighter, crisp sides like a quick salad or roasted Brussels sprouts — for a contrast in textures, try serving it with crunchy stuffed pickles such as these air-fryer stuffed pickles.

Why make this recipe

It turns inexpensive root vegetables into an elegant, comforting main or side.
The combination of Gruyère, sharp white cheddar and Parmesan gives a layered, complex cheesy flavor.
It’s ideal for holiday dinners or a cozy weeknight when you want a dish that’s impressive but not fussy.

Step-by-Step Guide to Making Cheesy Root Veggie Gratin

Ingredients

2 large Russet or Yukon Gold potatoes (about 1.5 lbs), peeled and thinly sliced
2 medium sweet potatoes (about 1.25 lbs), peeled and thinly sliced
3 medium carrots (about 0.75 lbs), peeled and thinly sliced
2 medium parsnips (about 0.5 lbs), peeled and thinly sliced
1 small celeriac (celery root) (about 0.5 lbs), peeled and thinly sliced (optional)
1 tablespoon olive oil or melted butter
1 teaspoon fresh thyme leaves, chopped
1/2 teaspoon salt
1/4 teaspoon black pepper

For the sauce:

4 tablespoons unsalted butter
4 tablespoons all-purpose flour
4 cups whole milk, warmed
1 cup heavy cream, warmed
2 cloves garlic, minced
1 small shallot, finely minced (or 1/4 small onion), finely minced
1/2 teaspoon freshly grated nutmeg
1 teaspoon salt
1/2 teaspoon white pepper
2 cups (about 8 oz) freshly grated Gruyère cheese, divided
1 cup (about 4 oz) freshly grated sharp white cheddar cheese, divided
1/2 cup (about 2 oz) freshly grated Parmesan cheese, divided
1/2 cup panko breadcrumbs (optional)
2 tablespoons melted butter (if using breadcrumbs)
Extra fresh thyme sprigs, for garnish

Directions

Prepare Root Vegetables
- Preheat your oven to 375°F (190°C). Butter a 9×13 inch baking dish.
- Peel all root vegetables (potatoes, sweet potatoes, carrots, parsnips, and optional celeriac). Using a mandoline or sharp knife, thinly slice all vegetables to about 1/8-inch thick.
- Place sliced vegetables in a large bowl, drizzle with 1 tablespoon olive oil or melted butter, sprinkle with 1 teaspoon fresh thyme leaves, 1/2 teaspoon salt, and 1/4 teaspoon black pepper, then toss gently to coat.
Craft Creamy Cheese Sauce
- In a large saucepan or Dutch oven, melt 4 tablespoons unsalted butter over medium heat. Add minced garlic and finely minced shallot (or onion), and sauté for 2–3 minutes until fragrant.
- Sprinkle in 4 tablespoons all-purpose flour, whisking continuously for 1–2 minutes to create a blonde roux. Gradually whisk in 4 cups warmed whole milk and 1 cup warmed heavy cream, ensuring a smooth mixture. Simmer gently for 5–7 minutes, whisking until the sauce thickens and coats the back of a spoon. Remove from heat.
Add Cheese to Sauce
- Stir 1/2 teaspoon freshly grated nutmeg, 1 teaspoon salt, and 1/2 teaspoon white pepper into the sauce. Add 1.5 cups of grated Gruyère, 0.75 cups of grated sharp white cheddar, and 0.25 cups of grated Parmesan cheese. Stir gently until all cheese has melted and the sauce is smooth and creamy. Taste and adjust seasoning as needed.
Assemble the Gratin Layers
- Spread a thin layer of the creamy cheese sauce on the bottom of the buttered baking dish. Arrange a single, even layer of sliced root vegetables over the sauce. Ladle a generous amount of sauce over the vegetables, then sprinkle with a small amount of the remaining grated cheeses (Gruyère, cheddar, and Parmesan). Repeat this layering process—vegetables, sauce, sprinkle of cheese—until all vegetables and sauce are used, pressing gently on each layer. The final layer should be sauce, fully covering the top.
Prepare Optional Topping (if desired)
- For an optional crunchy topping, combine 1/2 cup panko breadcrumbs with 2 tablespoons melted butter in a small bowl. Toss until coated. Sprinkle these buttery breadcrumbs over the top of the gratin. If not using breadcrumbs, generously cover the top with the remaining reserved grated cheeses.
Bake Covered
- Cover the baking dish tightly with aluminum foil. Bake in the preheated 375°F (190°C) oven for 45 minutes to steam the vegetables until tender.
Bake Uncovered to Golden Perfection
- Carefully remove the foil. Increase oven temperature to 400°F (200°C) (or maintain 375°F/190°C for slower browning). Return the uncovered gratin to the oven and bake for an additional 25–35 minutes, or until the top is deeply golden brown and bubbly, and a thin knife inserted into the center meets little resistance.
Rest Before Serving
- Remove the gratin from the oven and let it rest undisturbed on a wire rack for at least 15–20 minutes before serving. This allows the sauce to set and the layers to firm up for clean slicing. Garnish with extra fresh thyme sprigs if desired.

How to Store Cheesy Root Veggie Gratin

Refrigerator: Cool completely, cover tightly with foil or an airtight lid, and refrigerate for up to 4 days at 40°F (4°C) or below.
Freezer: For longer storage, assemble but do not bake, wrap tightly with plastic wrap and foil, and freeze for up to 2 months. Thaw in the refrigerator overnight before baking.
Reheating: Reheat individual slices in a preheated 350°F (175°C) oven for 15–20 minutes (cover with foil if browning too quickly) or microwave single portions until warmed through (1–2 minutes depending on power).

How to Present Cheesy Root Veggie Gratin

For family-style serving, place the gratin at the center of the table and garnish with a few fresh thyme sprigs and a dusting of finely grated Parmesan.
For plated presentation, use a broad spatula to lift even slices, wipe edges of the plates, and add a bright contrast like a small arugula salad dressed with lemon vinaigrette or roasted green beans with almonds.
Pairing: Serve alongside roasted chicken, glazed ham, or a nutty whole-grain loaf for a balanced meal.

Tips to Make Cheesy Root Veggie Gratin
Q: How do I keep it moist?
A: Make sure the milk and cream are warmed before adding to the roux and be generous with the cheese sauce layers—under-sauced gratins can dry out.

Q: Can I make this ahead?
A: Yes — assemble fully, cover tightly, and refrigerate overnight; bake as directed, adding 10–15 extra minutes covered if starting cold.

Q: How thin should I slice the vegetables?
A: Aim for about 1/8-inch thickness. Uniform slices cook evenly and stack nicely for clean servings.

Variation(s)

Vegetable swaps: If you don’t have celeriac, swap in more parsnip or add a thin layer of rutabaga. For a sweeter profile, increase the sweet potato ratio and use smoked cheddar for added depth.
Cheese changes: Replace half the Gruyère with Fontina for a slightly creamier melt, or use smoked Gouda in place of some cheddar for a smoky finish.

Why this gratin stands out
This gratin balances textures and flavors that root vegetables bring—earthy, sweet and starchy—with a silky, well-seasoned sauce and three complementary cheeses. The nutmeg gives a subtle warm note that elevates the creamy sauce without making it taste “spiced,” and a crisp breadcrumb or extra cheese crust adds the contrast of crunch that makes every forkful satisfying.

Serving ideas and meal plans

Holiday centerpiece: Serve as a side to roast beef or glazed ham and round out the plate with green beans almondine and cranberry chutney.
Vegetarian main: Make a green salad with mustard vinaigrette and add a crusty bread to make this gratin the main event for meat-free dinners.
Weeknight comfort: Pair with a simple roasted salmon fillet and lemon wedges for a fast, homey weeknight meal.

Common mistakes and how to avoid them

Not warming the dairy: Adding cold milk directly to the roux can cause lumps and a longer cooking time; warm milk and cream help the sauce come together smoothly.
Overbrowning the top: If the top is browning too quickly during the final baking, loosely tent with foil until the center is tender.
Uneven slices: Use a mandoline or take your time with a sharp knife—uneven slices will cause some layers to under- or over-cook.

FAQs
Q: Can I make this gratin dairy-free or vegan?
A: Replace butter with vegan margarine, use a plant-based milk that tolerates heat (like oat milk) plus a thickening agent, and swap cheeses for a vegan shredded cheese blend designed for melting; results will vary but you can get a pleasing gratin.

Q: Do I need to peel all the vegetables?
A: Peeling improves texture and appearance, especially for parsnips and celeriac, but thinly scrubbing and leaving skins on potatoes or carrots is fine if you prefer more rustic texture.

Q: How do I know when the gratin is done?
A: The center should be tender when tested with a thin knife (it should meet little resistance), and the top should be deeply golden and bubbly.

How to adapt this for dietary needs

Lower fat: Use 2% milk and reduce cream, or substitute half-and-half; decrease the total cheese slightly and add more seasoning to maintain flavor.
Gluten-free: Use a gluten-free all-purpose flour for the roux and gluten-free breadcrumbs.
Make-ahead / frozen: Assemble ahead and freeze unbaked for easy holiday prep; bake from frozen, covered, at 375°F (190°C) for 60–75 minutes, removing foil for the last 25–30 minutes to brown.

Technique notes and timing

Slicing: A mandoline delivers even, restaurant-quality slices quickly. If using a knife, stack and slice carefully; consistency is the secret to even cooking.
Roux and temperature: Cook the roux just until it smells slightly nutty but not brown; adding warm dairy helps the sauce thicken faster without scalding.
Layering: Press gently on layers to compact them slightly; this helps the completed gratin hold together for cleaner slices.

Leftover ideas

Thin slices of the gratin make an excellent base for a quick open-faced sandwich topped with arugula and a poached egg.
Cube leftover gratin and crisp in a skillet with a pat of butter for gratin hash, served with your favorite breakfast proteins.

A note on equipment

Baking dish: A 9×13 inch dish is recommended for the quantities listed; a slightly smaller dish will yield a deeper gratin but may require slightly longer baking.
Mandoline: Highly recommended if you want fast, even slices; always use the safety guard.
Oven thermometer: If you’re unsure of your oven’s true temperature, an oven thermometer helps ensure accurate baking and browning.

Final plating tips

Let it rest: Don’t rush to slice right out of the oven—letting it rest for 15–20 minutes improves slice integrity.
Garnish: Finish with fresh thyme and a little extra grated Parmesan for a professional touch.
Contrast: Add a bright, acidic element on the plate (lemon or a small salad) to cut through the richness.

Conclusion

This Cheesy Root Veggie Gratin is a versatile, crowd-pleasing dish that works as a comforting side or a satisfying vegetarian main; for inspiration from other cooks and slightly different versions to compare techniques and seasonings, take a look at this detailed take on a similar recipe from Cheesy Root Vegetable Gratin | Spoon Fork Bacon or explore a country-style approach at Root Vegetable Gratin – Weavers Orchard.