Cheesy Root Vegetable Gratin is a cozy, comforting dish that’s loaded with tender slices of sweet potatoes, carrots, and parsnips all baked in a creamy, cheesy sauce. The top gets golden and bubbly, making a perfect crispy layer that’s full of flavor. This gratin is a great way to enjoy root veggies in a rich and cheesy style, perfect for cooler days when you want something warm and satisfying.
I love making this gratin when I want an easy side that feels fancy without too much work. One tip I have is to slice the vegetables evenly so everything cooks at the same pace and gets beautifully soft all the way through. The cheesy sauce brings everything together, and sometimes I sneak in a bit of garlic for extra flavor—it’s always a hit! It’s one of those dishes people ask me to bring to dinners because it’s delicious and looks nice on the table.
My favorite way to enjoy this is alongside a simple roast chicken or even on its own with a fresh green salad. It’s like a warm, cheesy hug on a plate, and the root vegetables give it a nice, natural sweetness that balances the richness perfectly. Whenever I make this gratin, it reminds me of family meals and holiday dinners filled with laughter and good food.
Key Ingredients & Substitutions
Root Vegetables: Sweet potatoes, golden beets, Chioggia beets, and Yukon Gold potatoes all add different textures and colors. If you can’t find some, try parsnips or turnips—they’ll cook well and taste great too.
Cream & Milk: Heavy cream makes the sauce rich and silky. For a lighter option, you can use half-and-half or full-fat coconut milk, which adds a subtle coconut flavor that pairs well with the earthiness of the roots.
Cheese: Gruyère is my favorite for melting and flavor. If you want something easier to find, Swiss or Fontina works well. Parmesan adds a nice sharp note on top—try Pecorino Romano if you want to switch it up.
Thyme & Garlic: Fresh thyme brings a lovely herbal aroma, but dried thyme is a fine substitute—just use less. Garlic adds warmth and depth; roasted garlic could work too if you prefer a milder taste.
How Can I Get My Root Vegetables Tender but Not Mushy?
Slicing your vegetables evenly is key—aim for about ⅛-inch thickness. This helps them cook at the same rate. Use a sharp knife or mandoline for better control.
- Layer the slices flat in the dish without overlapping too much, which avoids soggy spots.
- Pour warm cream mixture over the veggies to start the cooking gently.
- Cover the dish for most of the baking time to trap steam and soften the roots.
- Uncover at the end to let the top brown and develop a crispy crust.
Wait about 10 minutes before serving so the sauce sets and the slices firm up slightly. This improves texture and makes serving easier!
Equipment You’ll Need
- 9×13 inch baking dish – perfect size for layering vegetables evenly and baking the gratin.
- Mandoline slicer or sharp knife – helps you slice vegetables thinly and evenly for even cooking.
- Medium saucepan – to gently heat the cream, milk, garlic, and herbs before pouring over the vegetables.
- Mixing bowl – for combining ingredients or holding sliced veggies before assembling.
- Aluminum foil – to cover the dish during baking and keep the moisture in.
Flavor Variations & Add-Ins
- Add cooked crumbled bacon or pancetta for a smoky, salty touch that pairs well with cheese.
- Swap Gruyère for sharp cheddar or fontina for a different cheesy flavor profile.
- Include thinly sliced leeks or caramelized onions between layers for extra sweetness and aroma.
- Stir in fresh rosemary or sage with thyme for a more herb-forward, earthy taste.
How to Make Cheesy Root Vegetable Gratin?
Ingredients You’ll Need:
Root Vegetables:
- 2 medium sweet potatoes (orange-fleshed), thinly sliced
- 2 medium golden beets, thinly sliced
- 2 medium Chioggia beets (or red/purple beets), thinly sliced
- 2 medium Yukon Gold potatoes, thinly sliced
Sauce & Cheese:
- 2 cups heavy cream
- 1 cup whole milk
- 3 cloves garlic, minced
- 1½ cups Gruyère cheese, grated
- ½ cup Parmesan cheese, grated
- 1 tbsp fresh thyme leaves, chopped (plus extra for garnish)
- Salt and freshly ground black pepper, to taste
- Butter, for greasing the baking dish
How Much Time Will You Need?
This dish takes about 15-20 minutes for prep, primarily slicing vegetables and mixing the cream sauce, plus about 1 hour for baking and resting. Altogether, plan for around 1 hour and 20 minutes to enjoy this creamy, cheesy gratin.
Step-by-Step Instructions:
1. Prepare the Oven and Dish:
Preheat your oven to 375°F (190°C). Generously butter a 9×13 inch baking dish to make sure nothing sticks.
2. Make the Cream Mixture:
In a medium saucepan, combine the heavy cream, whole milk, minced garlic, and half of the chopped thyme. Heat over medium heat until the mixture just starts to simmer, then remove it from the heat.
3. Layer the Vegetables:
Start with a layer of Yukon Gold potato slices evenly spread on the bottom of your baking dish. Next, add a layer of sweet potato slices, then golden beets, and finally purple (Chioggia) beets. Arrange them in rows or sections for a colorful presentation like in the photo.
4. Season and Add Cheese Between Layers:
Lightly season each vegetable layer with salt and freshly ground black pepper. Sprinkle a bit of the grated Gruyère cheese over each layer to add richness and flavor.
5. Pour the Cream Sauce:
Pour the warm cream mixture evenly over the arranged vegetables. Press down gently so the cream seeps between all the slices, helping cook them evenly.
6. Add the Final Cheese Topping:
Top the gratin with the remaining Gruyère and Parmesan cheeses. This will create a bubbly, golden crust during baking.
7. Bake Covered:
Cover the baking dish loosely with aluminum foil and bake for 45 minutes. This traps moisture so the vegetables cook tender without drying out.
8. Finish Baking Uncovered:
Remove the foil and bake for another 20-25 minutes, or until the vegetables are fork-tender and the top is nicely browned and bubbling.
9. Rest and Garnish:
Let the gratin cool for about 10 minutes before serving so the sauce can thicken. Garnish with additional fresh thyme leaves for a bright, herbal finish.
This delicious Cheesy Root Vegetable Gratin makes a wonderful side dish with roasts or can be served on its own for a comforting vegetarian meal. Enjoy the blend of sweet, earthy veggies and rich, cheesy goodness!
Can I Use Frozen Root Vegetables for This Gratin?
While fresh vegetables are best for even cooking and texture, you can use frozen root vegetables if they are fully thawed and patted dry to avoid extra moisture. Adjust baking time slightly, checking tenderness as you go.
How Should I Store and Reheat Leftovers?
Store leftover gratin in an airtight container in the fridge for up to 3 days. Reheat in the oven at 350°F (175°C) until warmed through to keep the top crispy, or use the microwave for a quicker option but softer texture.
Can I Make This Gratin Ahead of Time?
Yes! Assemble the gratin and refrigerate it uncovered for up to 24 hours before baking. If refrigerated covered, allow it to come to room temperature before baking for even cooking.
What Are Good Substitutions for the Cheeses?
If you can’t find Gruyère, Swiss or Fontina are great alternatives that melt well. For Parmesan, Pecorino Romano or Asiago cheese can be used to maintain that sharp, savory topping flavor.