Winter Vegetable Gratin

Last January, I stood in my kitchen staring at a pile of root vegetables from the farmer's market, wondering what to do with them all. The butternut squash was so dense I nearly dulled my knife, and the parsnips had that earthy sweetness I'd forgotten about. I layered them into a dish with cream and cheese, and what came out of the oven was this golden, bubbling masterpiece that made the whole house smell like a French bistro.

I made this for a small dinner party during a snowstorm, and nobody left the table until the dish was scraped clean. My friend Sophie, who usually avoids anything beige, went back for thirds. We sat around with wine and crusty bread, and the gratin became the centerpiece of the evening without me even planning it that way.

Ingredients

• Potatoes: Use waxy varieties like Yukon Gold so they hold their shape and don't turn mushy under all that cream.
• Butternut squash: Its sweetness balances the savory cheese, and it roasts into tender, caramelized layers.
• Parsnips: They add a subtle, nutty flavor that deepens as they bake.
• Carrots: Slice them thin so they cook evenly with the other vegetables.
• Leek: Milder than onions, it melts into the sauce and adds a delicate sweetness.
• Garlic: Fresh minced garlic gives the dish warmth without overpowering the vegetables.
• Whole milk and heavy cream: This combination creates a sauce that's rich but not too thick.
• Butter and flour: The base of your roux, which thickens the sauce and keeps it silky.
• Dijon mustard: Just a teaspoon cuts through the richness and adds a subtle tang.
• Nutmeg: A little goes a long way, it brings out the sweetness in the vegetables.
• Gruyere cheese: Melts beautifully and has that nutty, slightly sweet flavor that makes gratins unforgettable.
• Parmesan: Adds sharpness and helps the top get golden and crispy.
• Breadcrumbs: Fresh ones create texture, toasted ones add even more crunch.
• Fresh thyme: Its earthy, lemony notes tie everything together.

Instructions

Prep the oven and dish:

Preheat your oven to 375 degrees and grease a 9x13 inch baking dish generously. This keeps the edges from sticking and makes cleanup easier.

Make the roux:

Melt butter in a saucepan over medium heat, then whisk in the flour and cook for a minute or two until it smells toasty. This step cooks out the raw flour taste.

Build the sauce:

Slowly pour in the milk and cream, whisking constantly so no lumps form. Stir in the mustard, nutmeg, salt, and pepper, then let it bubble gently until it coats the back of a spoon.

Add the cheese:

Remove the pan from heat and stir in half the Gruyere until it melts into the sauce. It should be smooth and glossy.

Season the vegetables:

Toss all your sliced vegetables with the garlic, salt, pepper, and half the thyme in a big bowl. Get your hands in there so everything's evenly coated.

Layer the gratin:

Spread half the vegetables in the baking dish, pour over half the sauce, then repeat. Press down gently so the sauce seeps between the layers.

Top it off:

Sprinkle the remaining Gruyere, all the Parmesan, breadcrumbs, and thyme over the top. This creates that irresistible golden crust.

Bake covered, then uncovered:

Cover loosely with foil and bake for 35 minutes, then remove the foil and bake another 15 minutes until the top is golden and the vegetables are fork tender. Let it rest for 10 minutes before serving so the layers set.

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The first time I brought this to a potluck, someone asked if I'd trained in France. I laughed and said no, just a lot of winter Sundays with too many root vegetables and not enough imagination. But that's the magic of a gratin, it takes the ordinary and makes it feel special.

How to Store and Reheat

Cover leftovers tightly with foil or transfer to an airtight container and refrigerate for up to four days. Reheat in a 350 degree oven until warmed through, about 20 minutes, or microwave individual portions. The sauce might look a little separated when cold, but it comes back together beautifully when heated.

Swaps and Substitutions

If you don't have Gruyere, sharp white Cheddar or Emmental work just as well. Swap the parsnips for turnips or celery root if that's what you have. For a lighter version, use half and half instead of cream, though the sauce won't be quite as luscious. You can also make this vegan with plant-based milk, cream, and cheese, just be sure to choose brands that melt well.

Serving Suggestions

This gratin shines as a side dish next to roast chicken, beef, or lamb, but it's hearty enough to serve as a main with a crisp green salad and good bread. I love it with a simple arugula salad dressed in lemon and olive oil to cut through the richness. A glass of dry white wine or a light red like Pinot Noir pairs beautifully.

• Add a pinch of chili flakes to the sauce for a gentle kick of heat.
• Stir in some sauteed mushrooms between the layers for extra umami.
• Garnish with extra fresh thyme or a sprinkle of flaky sea salt before serving.

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There's something deeply satisfying about pulling a bubbling, golden gratin from the oven on a cold night. It's the kind of dish that makes you slow down, gather around the table, and savor every bite.

Recipe Questions & Answers

→ What vegetables are used in this gratin?

It includes potatoes, butternut squash, parsnips, carrots, leek, and garlic.

→ How is the creamy sauce prepared?

Butter and flour are cooked to form a roux, then milk and cream are whisked in with Dijon mustard, nutmeg, salt, and pepper until thickened.

→ Can this dish be made gluten-free?

Yes, by substituting all-purpose flour and breadcrumbs with gluten-free alternatives.

→ What cheeses are used for topping?

Gruyère and Parmesan cheeses provide a rich, golden topping along with fresh thyme and breadcrumbs.

→ Are there any tips for extra flavor?

Adding a pinch of chili flakes enhances warmth, or substituting Gruyère with sharp Cheddar or Emmental provides variation.

→ How long should it rest after baking?

Let the gratin rest for about 10 minutes before serving to allow the flavors to meld and the dish to firm up slightly.