Is there anything more comforting than a bubbling, golden-brown dish coming out of the oven on a chilly evening? This Cheesy Root Vegetable Gratin is that cozy hug in casserole form. It transforms humble, earthy veggies into a rich, creamy, and impossibly cheesy side dish that steals the show at any table. It’s a hands-off recipe that does most of the work in the oven, leaving you free to tackle the rest of supper. And honestly, the way the Gruyère gets all crispy and brown on top? So good. You’re going to love how this recipe makes even the pickiest eater at your table ask for a second helping of vegetables.
Ingredients
- 1 large russet potato (about 1 lb): Provides a sturdy, starchy base that holds its shape.
- 1 large sweet potato (about ¾ lb): Adds a touch of natural sweetness and vibrant color.
- 2 medium parsnips: Offers a slightly peppery, sweet flavor that complements the other roots.
- 1 medium turnip: Brings a pleasant, mild bitterness that balances the richness.
- 1 ½ cups heavy cream: Creates the luxuriously creamy sauce that binds everything together.
- 2 cloves garlic, minced: Infuses the cream with a savory, aromatic punch.
- 1 tsp fresh thyme leaves: Lends a classic, earthy herb flavor.
- 1 ½ cups shredded Gruyère cheese, divided: Melts beautifully for that signature nutty, gooey goodness.
- ½ cup grated Parmesan cheese: Adds a sharp, salty kick and helps form a crisp top crust.
- 1 tsp kosher salt: Enhances all the natural flavors of the vegetables and sauce.
- ½ tsp black pepper: Provides a subtle, essential spice.
- Butter for greasing: Prevents sticking and adds a hint of rich flavor.
Step by Step Method
- Preheat your oven to 375°F (190°C). Take a 2-quart baking dish and grease it generously with butter.
- Peel all the root vegetables: the russet potato, sweet potato, parsnips, and turnip. Using a sharp knife or a mandoline slicer for even cooking, slice them all into ⅛-inch thick rounds.
- In a large bowl, combine the heavy cream, minced garlic, thyme, salt, and pepper. Whisk it all together. Add all of the sliced vegetables to the bowl and toss gently with your hands to ensure every single piece is coated in that creamy, herby mixture.
- Take half of the shredded Gruyère cheese and all of the Parmesan cheese, and sprinkle it over the veggie mixture. Toss again to distribute the cheese throughout.
- Transfer the vegetable and cream mixture to your prepared baking dish, arranging the slices as evenly as you can. Press it all down gently. Pour any remaining cream left in the bowl over the top.
- Cover the dish tightly with foil and bake for 40 minutes. The foil traps steam to cook the vegetables until they’re just tender.
- Carefully remove the foil. Sprinkle the remaining Gruyère cheese evenly over the top. Return the dish to the oven, uncovered, and bake for another 20-25 minutes. You’re looking for the top to be a beautiful golden brown and the cream to be bubbling vigorously around the edges.
- Let the gratin rest for about 10 minutes before serving. This allows the creamy sauce to thicken up just right.
What Is Cheesy Root Vegetable Gratin?
At its heart, a gratin is any baked dish that gets a gorgeous, toasted top crust, often thanks to breadcrumbs or cheese. This version skips the breadcrumbs and lets the cheese do all the talking. We’re taking a mix of winter root vegetables—each bringing its own unique flavor and texture—and baking them low and slow in a rich, garlicky cream sauce until they’re meltingly tender. The result is a decadent, crowd-pleasing vegetable side dish that feels both humble and extravagant all at once. It’s the kind of recipe that turns a simple weeknight roast chicken into a special occasion.
Oven Temperatures for Perfect Gratin
Getting the oven temperature right is the secret to a gratin where the vegetables are fully cooked and the top is perfectly browned, not burned. 375°F (190°C) is the sweet spot. It’s hot enough to cook the vegetables through in a reasonable time and encourage good browning on the cheese, but not so hot that the cream sauce breaks or the top scorches before the middle is done. If you find your cheese is browning too quickly in those final uncovered minutes, just lay a loose piece of foil over the top. Every oven is a little different, so keep an eye on it!
Creative Variations for Root Vegetable Gratin
The beauty of a root vegetable gratin is its flexibility. Don’t be afraid to play with what you have! Try swapping in different roots like celery root, yucca, or even thin slices of butternut squash. For a flavor twist, add a pinch of nutmeg to the cream or swap the thyme for chopped rosemary. If you’re looking for a bit of smoky flavor without pork, a few tablespoons of finely chopped smoked turkey stirred into the layers is a fantastic addition. And for a lighter version, you can substitute half-and-half for the heavy cream, though the sauce won’t be *quite* as luxuriously thick.
Serving Ideas & Pairings for Vegetable Sides
This gratin is the ultimate supporting actor that can handle any main dish you pair it with. It’s a classic holiday side, right up there with green bean casserole, but it’s hearty enough for a simple Sunday supper, too. Serve it alongside a perfectly roasted turkey or a juicy roasted chicken. It’s also fantastic with a pan-seared pork chop or a thick, juicy steak. For a lighter meal, a simple arugula salad with a bright lemon vinaigrette on the side cuts through the richness beautifully. Honestly, it’s so flavorful it can almost be a meal on its own with a hunk of crusty bread.
Storage Tips for Leftover Gratin
Leftovers? Lucky you! Let the gratin cool completely, then cover the baking dish tightly with plastic wrap or transfer portions to an airtight container. It will keep in the refrigerator for up to 4 days. To reheat, your oven is your best friend. Pop individual portions or the whole dish (if you covered it with foil) into a 350°F oven for 15-20 minutes, until heated through. The microwave will work in a pinch, but it can make the vegetables a bit soft and the sauce a little oily. I don’t recommend freezing this one, as the creamy sauce can separate and the vegetables will become watery when thawed.
Doneness Test for Perfectly Cooked Vegetables
How do you know when your vegetable gratin is done? The visual cues are your best guide. The top should be a deep, appetizing golden brown, and the creamy sauce should be bubbling actively around the edges of the dish. But the real test is the tenderness of the vegetables. Take a thin, sharp knife and carefully poke it into the center of the gratin. It should slide into the vegetables with absolutely no resistance. If you feel any hard spots, cover it back up with foil and give it another 5-10 minutes in the oven. They should be so, so tender.
FAQs About Vegetable Gratin Recipes
- Can I make this root vegetable gratin ahead of time? Absolutely! You can assemble the entire dish up to the point of baking, cover it tightly, and refrigerate it for up to 24 hours. Let it sit on the counter for about 30 minutes before baking, then add an extra 5-10 minutes to the covered baking time since it will be going into the oven cold.
- What’s the best cheese to use if I can’t find Gruyère? Gruyère is classic for its superb melting quality and nutty flavor, but a good Swiss cheese or even a sharp white cheddar are excellent substitutes in vegetable dishes. You’ll still get that wonderful cheesy pull and flavor.
- Do I have to use a mandoline to slice the vegetables? While a mandoline gives you super consistent, thin slices that cook evenly, a sharp chef’s knife and a steady hand will work just fine. Just try your best to keep the slices around ⅛-inch thick so everything is done at the same time.
- My gratin came out a bit watery. What happened? Some vegetables, especially potatoes, release water as they cook. This is usually due to not slicing them thinly enough or not baking it long enough uncovered to allow some of the liquid to evaporate and thicken. Letting it rest after baking is also crucial for the sauce to set.