Cheesy Root Vegetable Gratin is a cozy, comforting dish that brings together tender root vegetables baked in a creamy, cheesy sauce. You get the natural sweetness from carrots, parsnips, and potatoes paired with the melty, golden cheese on top that makes every bite feel special and homey.
I love making this gratin when I want something satisfying but still a little special on the table. It’s the kind of dish that’s easy to prepare ahead of time and makes the whole house smell amazing as it bakes. The combination of cream, cheese, and those earthy root veggies always wins over even the pickiest eaters at my place.
My favorite way to enjoy this gratin is alongside a simple green salad or roasted chicken for a complete meal. It’s perfect for sharing with family or friends, especially on chilly evenings when everyone wants something warm and filling. I find it’s best served fresh from the oven, with the cheese bubbling and a little crispy on top.
Key Ingredients & Substitutions
Root Vegetables: Carrots, potatoes, and parsnips are great for texture and natural sweetness. You can swap parsnips with sweet potatoes or turnips if you like. Just keep the slices thin so they cook evenly.
Cream and Milk: Heavy cream makes the sauce rich and smooth, but you can use half-and-half or whole milk for a lighter version. Avoid skim milk as it won’t give the same creamy texture.
Cheese: Gruyère is perfect for meltiness and flavor here. Parmesan adds a nutty, salty kick on top. If you can’t find Gruyère, try Swiss, Fontina, or even sharp cheddar for a twist.
Herbs: Fresh thyme gives a subtle earthy note. Rosemary or sage are tasty alternatives. Dried herbs work well too, just use about a third of the quantity.
How Can You Get Those Thin, Even Vegetable Slices?
Slicing vegetables evenly is key to even cooking and a nice look. Here’s how to do it:
- Use a sharp knife or a mandoline slicer for uniform thin slices, about 1/8 inch thick.
- If using a knife, try to keep steady hands and slice slowly for control.
- Keep the slices similar thickness so all vegetables cook at the same rate without some turning mushy or staying hard.
- Arranging them upright and overlapping helps the gratin cook evenly and look pretty when served.
Equipment You’ll Need
- Mandoline slicer or sharp knife – I recommend a mandoline for easy, even slices that cook uniformly.
- Large saucepan – for warming the cream mixture; it makes blending the flavors simple.
- Baking dish (oval or rectangular) – a 9×13-inch or similar size dish works well and heats evenly.
- Brush or paper towel – to lightly butter the dish for easy removal and a golden crust.
- Measuring cups and spoons – for precise ingredient portions, ensuring the recipe turns out just right.
Flavor Variations & Add-Ins
- Swap Gruyère for sharp cheddar or Swiss cheese for a different melt and flavor profile.
- Mix in cooked, crumbled bacon or sautéed mushrooms for extra richness and texture.
- Add a layer of cooked leeks or caramelized onions for sweetness and depth.
- Use fresh herbs like rosemary or sage instead of thyme to change up the aroma and taste.
Cheesy Root Vegetable Gratin
Ingredients You’ll Need:
Root Vegetables:
- 3 large carrots, peeled and thinly sliced
- 3 large golden potatoes, peeled and thinly sliced
- 2 large parsnips, peeled and thinly sliced
Creamy Sauce & Cheese:
- 1 ½ cups heavy cream
- 1 ½ cups whole milk
- 2 cloves garlic, minced
- 1 ½ cups Gruyère cheese, grated
- ½ cup Parmesan cheese, grated
Seasonings & Extras:
- 1 tablespoon fresh thyme leaves (or 1 teaspoon dried thyme)
- 2 tablespoons unsalted butter (for greasing the dish)
- Salt and freshly ground black pepper, to taste
- Fresh herbs (such as thyme or rosemary) for garnish
How Much Time Will You Need?
This dish takes about 20 minutes to prepare, including peeling and slicing the vegetables and getting the sauce ready. Then, bake covered for 40 minutes, followed by another 20-25 minutes uncovered to get the cheese golden and bubbly. Allow 10 minutes for resting before serving. Total time is roughly 1 hour 30 minutes.
Step-by-Step Instructions:
1. Prepare and Butter Your Dish:
Preheat your oven to 375°F (190°C). Use the butter to lightly grease a large oval or rectangular baking dish. This helps the vegetables and cheese bake evenly and prevents sticking.
2. Warm The Cream Mixture:
In a medium saucepan, combine the heavy cream, whole milk, minced garlic, salt, and black pepper. Warm this gently on low heat without letting it boil. This allows the garlic to infuse into the creamy sauce and flavors to meld.
3. Arrange The Vegetables:
Thinly slice your carrots, potatoes, and parsnips. Arrange them upright in the buttered baking dish, alternating the vegetable slices in a neat, overlapping pattern. As you go, sprinkle a little salt, pepper, and thyme over the layers for added flavor.
4. Add Cream and Cheese:
Pour the warm cream mixture evenly over the arranged vegetables. Then sprinkle the grated Gruyère cheese generously on top, followed by the Parmesan cheese for a tasty, golden crust.
5. Bake Covered, Then Uncovered:
Cover the dish loosely with foil and bake in your preheated oven for about 40 minutes. Then remove the foil and bake for an extra 20-25 minutes, or until the cheese on top is bubbly, golden, and slightly crispy.
6. Rest and Serve:
Take the gratin out of the oven and let it rest for about 10 minutes. This helps it set and makes it easier to serve. Garnish with fresh herbs if you like, then enjoy your warm, cheesy, comforting gratin as a side or main dish!
Can I Use Frozen Vegetables for This Gratin?
Frozen vegetables can work, but thaw and pat them dry well to avoid excess moisture. Since frozen slices may release more water, baking time might be a bit longer to achieve a crispy top.
How Do I Store Leftovers?
Store any leftovers in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave, covering loosely to keep the cheese from drying out.
Can I Prepare This Dish Ahead of Time?
Yes! Assemble the gratin up to the point of baking, cover it tightly, and refrigerate for up to 24 hours. Bake as directed, just add a few extra minutes if it’s cooking from cold.
What Cheese Can I Substitute If I Don’t Have Gruyère?
Swiss, Fontina, or sharp cheddar are great alternatives—they melt well and complement the flavors nicely. Just use the same quantity as the Gruyère in the recipe.
