Cheesy Root Vegetable Gratin is a comforting dish that brings together tender slices of root veggies like potatoes, carrots, and parsnips baked in a rich, cheesy sauce. It’s all golden and bubbly on top with a crispy edge, making it the perfect side for chilly evenings or holiday dinners.
I love making this gratin when I want something that feels like a warm hug on a plate. The mix of different root vegetables gives it a lovely variety of textures—soft and creamy inside with just enough bite—and the cheese makes everything extra cozy. It’s one of those dishes that’s easy to prepare but always impresses friends and family.
My favorite way to enjoy this gratin is alongside a simple roasted chicken or a green salad to balance out the richness. It also reheats really well, so I usually make a bit extra so I can enjoy it for a couple of days. Honestly, it’s great comfort food that feels a little special every time.
Key Ingredients & Substitutions
Root vegetables: Potatoes, sweet potatoes, and beets create a mix of sweet and earthy flavors. If you can’t find golden beets, you can swap with turnips or rutabaga for a similar texture. Just peel and slice evenly for even cooking.
Gruyère cheese: It melts beautifully and adds a nutty flavor. If you can’t find it, use a mix of sharp cheddar and Parmesan, or Fontina for a creamier taste. Fresh cheese makes the gratin richer.
Heavy cream and milk: These create a creamy sauce. For a lighter version, use half-and-half or full-fat coconut milk but expect a slightly different flavor. Make sure the cream mixture is warmed gently so it infuses the veggies well.
Herbs & seasoning: Fresh thyme adds a lovely aroma. Feel free to try rosemary or sage as a swap. Don’t skip the garlic—it boosts the overall taste significantly.
How Can I Get Tender Veggies and a Golden Crispy Top?
Balancing tender vegetables with a crispy cheesy topping is key. Here’s how:
- Slice veggies thin and uniform to ensure even cooking.
- Warm the cream mixture before pouring it over veggies to help them cook gently.
- Cover with foil initially to trap steam and soften veggies.
- Remove foil near the end to brown the cheese and get that golden crust.
- Let the gratin rest for a few minutes before slicing so the sauce thickens and slices hold their shape.
Equipment You’ll Need
- Baking dish (9×13 inches or similar) – perfect size to layer vegetables and bake evenly.
- Sharp knife or mandoline slicer – helps you get uniform, thin slices for even cooking.
- Large mixing bowl – to toss the sliced veggies if needed before arranging.
- Medium saucepan – for warming the cream and seasoning mixture gently.
- Aluminum foil – to cover the gratin during the first part of baking and keep it moist.
- Cheese grater – for shredding your Gruyère or other cheese fresh for better melt.
Flavor Variations & Add-Ins
- Add caramelized onions between layers for a sweet, rich twist that pairs nicely with the root veggies.
- Mix in cooked crumbled bacon or pancetta for a smoky, salty boost that brightens the creamy dish.
- Try replacing some root veggies with thin slices of cauliflower or fennel for a different texture and subtle flavor.
- Sprinkle fresh chopped rosemary or sage on top before baking for an herbal note that lifts the richness.
How to Make Cheesy Root Vegetable Gratin
Ingredients You’ll Need:
Vegetables:
- 2 medium potatoes, peeled and thinly sliced
- 2 medium sweet potatoes, peeled and thinly sliced
- 2 medium golden beets, peeled and thinly sliced
- 2 medium red beets, peeled and thinly sliced
Sauce and Cheese:
- 3 cups shredded Gruyère cheese (or a mix of Gruyère and Parmesan)
- 2 cups heavy cream
- 1 cup whole milk
- 3 cloves garlic, minced
- 1 tbsp fresh thyme leaves (or 1 tsp dried thyme)
- Salt and freshly ground black pepper, to taste
- 2 tbsp unsalted butter, for greasing the dish
- Optional: pinch of nutmeg
How Much Time Will You Need?
This recipe takes about 15 minutes to prepare and around 55-60 minutes to bake. You’ll spend time slicing vegetables, heating the cream sauce, and layering everything before baking the gratin until tender and golden on top. Allow a few minutes to cool before serving.
Step-by-Step Instructions:
1. Prepare Your Oven and Baking Dish:
Heat your oven to 375°F (190°C). Lightly grease a medium to large baking dish with butter so your gratin doesn’t stick.
2. Make the Creamy Sauce:
In a saucepan over medium heat, combine heavy cream, whole milk, minced garlic, thyme, salt, pepper, and a pinch of nutmeg if you like. Warm the mixture gently until fragrant but don’t let it boil. Then take it off the heat.
3. Layer the Vegetables:
Arrange the sliced potatoes, sweet potatoes, golden beets, and red beets in your baking dish. Lay them in rows or alternating patterns, slightly overlapping each slice to create a pretty, colorful look.
4. Add Sauce and Cheese:
Pour the warm cream mixture evenly over the arranged vegetables so it seeps through the layers. Sprinkle about two-thirds of your shredded cheese evenly on top.
5. Bake Covered:
Cover the dish tightly with aluminum foil. Bake in the oven for about 40 minutes, or until you can easily pierce the vegetables with a knife and they’re tender.
6. Bake Uncovered for a Golden Top:
Remove the foil and sprinkle the remaining cheese over the gratin. Bake uncovered for another 15-20 minutes until the cheese is bubbly and golden brown.
7. Let It Rest and Serve:
Take the gratin out and let it cool for 5 to 10 minutes. This helps the creamy sauce thicken a bit, making it easier to cut neat slices. Garnish with fresh thyme or herbs of your choice and serve warm with your favorite main dish.
Can I Use Frozen Root Vegetables for This Gratin?
You can use frozen vegetables, but it’s best to thaw them completely and pat dry to remove excess moisture. This helps prevent a watery gratin and ensures even cooking.
Can I Make This Gratin Ahead of Time?
Absolutely! Prepare the gratin up to step 5, cover it, and refrigerate for up to 24 hours. When ready, bake covered for about 45 minutes, then uncover to brown the cheese as directed.
What’s the Best Way to 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 if it seems dry.
Can I Substitute Other Cheeses?
Yes! If Gruyère isn’t available, try Fontina, cheddar, or a mix of Parmesan and mozzarella for good melt and flavor balance.