Cheesy Root Vegetable Gratin is a comforting mix of tender, earthy root veggies like potatoes, carrots, and parsnips baked in a creamy cheese sauce until golden and bubbly on top. The cheesy crust adds a lovely richness that brings all the flavors together in the best way.
I love making this dish when I want something warm and satisfying without too much fuss. It’s kind of like a hug on a plate, especially during chilly months. I usually add a little garlic and thyme to give it a fresh, cozy lift. Plus, the leftovers taste just as good the next day!
My favorite way to enjoy this gratin is as a side with roasted chicken or a simple green salad. It’s perfect for family dinners or holiday meals because it feels special but is easy to prepare. If you’re a fan of cheese and veggies, this gratin will quickly become a go-to in your kitchen.
Key Ingredients & Substitutions
Beets: These give a sweet earthiness and color contrast. If you don’t have beets, try purple sweet potatoes or skip them for a milder flavor.
Sweet Potatoes: They add natural sweetness and creaminess. You could swap with butternut squash or regular white potatoes for less sweetness.
Gruyère Cheese: It melts beautifully and adds a nutty taste. If unavailable, cheddar, fontina, or mozzarella work well.
Cream and Milk: The creamy base is key to a luscious sauce. For a lighter version, use half-and-half or whole milk only.
Thyme and Garlic: These herbs add freshness and depth. Feel free to experiment with rosemary or sage for a slightly different note.
How Do I Get Thin, Even Vegetable Slices for a Perfect Gratin?
Getting uniformly thin slices ensures even cooking and a nice texture. Here’s how:
- Use a sharp knife or mandoline slicer for best results—mandolines give quick, even slices.
- Peel vegetables first for tender bites and to help the cream soak in better.
- Slice about 1/8 inch thick; thinner slices cook faster and layer nicely.
- Arrange slices overlapping slightly to help everything cook evenly and look pretty.
Taking time here makes the gratin cook evenly without any crunchy bits and gives a lovely creamy texture.
Equipment You’ll Need
- Mandoline slicer – helps you get even, thin slices quickly and safely for uniform cooking.
- Medium saucepan – perfect for gently warming the cream and infusing the garlic and thyme.
- 9×13-inch baking dish – roomy enough to layer veggies and let them cook evenly with a golden top.
- Aluminum foil – covers the dish to keep moisture in while baking so veggies stay tender.
- Sharp knife – essential if you don’t have a mandoline; just take your time for thin slices.
Flavor Variations & Add-Ins
- Add cooked bacon or pancetta bits for a smoky, salty pop that contrasts the creamy veggies.
- Mix in sliced mushrooms or caramelized onions for extra umami and texture.
- Swap Gruyère for sharp cheddar or mozzarella depending on your cheese taste preference.
- Sprinkle fresh rosemary or sage instead of thyme for a different herb flavor that pairs well with root veggies.
Cheesy Root Vegetable Gratin
Ingredients You’ll Need:
Vegetables:
- 2 medium beets, peeled and thinly sliced
- 2 medium sweet potatoes, peeled and thinly sliced
- 2 medium yellow potatoes, peeled and thinly sliced
- 1 medium parsnip, peeled and thinly sliced (optional)
Creamy Sauce & Cheese:
- 2 cups heavy cream
- 1 cup whole milk
- 3 cloves garlic, minced
- 1 tsp fresh thyme leaves (or ½ tsp dried thyme)
- 1 ½ cups shredded Gruyère cheese (or sharp cheddar or fontina)
- ½ cup grated Parmesan cheese
Other:
- Salt and freshly ground black pepper, to taste
- 1 tbsp unsalted butter (for greasing the baking dish)
How Much Time Will You Need?
This recipe takes about 20 minutes of prep time to slice vegetables and prepare the cream sauce. Then, you’ll bake it covered for 40 minutes and uncovered for another 20–25 minutes, plus a 10-minute rest before serving. Total time: roughly 1 hour 30 minutes.
Step-by-Step Instructions:
1. Prepare the Oven and Dish:
Preheat your oven to 375°F (190°C). Grease a medium-sized (about 9×13 inch) baking dish with butter to prevent sticking.
2. Make the Creamy Sauce:
In a saucepan, combine the heavy cream, whole milk, minced garlic, and thyme. Heat over medium until it gently simmers (small bubbles around the edge). Remove from heat once it’s warm and fragrant.
3. Layer the Vegetables:
Arrange the thin vegetable slices in rows or an alternating pattern inside the prepared baking dish. Overlap the slices a little to create a neat layered look and even cooking.
4. Season and Add Cheese:
Sprinkle salt and pepper generously over the veggies. Pour the warm cream mixture evenly over the vegetables. Next, spread the shredded Gruyère cheese evenly on top, and sprinkle with the Parmesan cheese.
5. Bake Covered and Then Uncovered:
Cover the dish with foil to keep moisture in and bake for 40 minutes. Then, remove the foil and bake uncovered for 20–25 minutes more, until the cheese is golden and bubbly and the vegetables are tender when tested with a fork.
6. Rest and Serve:
Allow the gratin to rest for about 10 minutes after baking to let it set. Serve warm as a delicious, cheesy, and comforting side dish that pairs wonderfully with many main courses.
Can I Use Frozen Vegetables for This Gratin?
It’s best to use fresh vegetables for this recipe because frozen root veggies can release excess moisture and become mushy. If you must use frozen, thaw and pat them very dry before slicing and layering.
How Do I Store Leftovers?
Store leftover gratin in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave until warmed through, adding a splash of cream or milk if it seems a bit dry.
Can I Make This Dish Ahead of Time?
Yes! You can assemble the gratin and keep it covered in the fridge for up to 24 hours before baking. When ready, bake it straight from the fridge, adding about 10 extra minutes to the baking time.
What Are Good Cheese Substitutes?
If you don’t have Gruyère, cheddar, fontina, or mozzarella are perfect melty alternatives. Just choose cheeses that melt well and complement the creamy sauce.
