What’s in this Root Vegetable Gratin:
- Root vegetables like purple sweet potato, yams, and parsnips make up the majority of this dish. I also added butternut squash. Although not technically a root vegetable, its sweet flavors mingle nicely with the earthy root vegetables and balance the dish nicely.
- A mixture of Gruyere, Parmesan, garlic, thyme and cream is used to bring the dish together while baking.
- Extra cheese is sprinkled on top of the dish just before baking, and it’s garnished with additional fresh thyme after being removed from the oven.
Tips and Tricks:
- Since baking dish sizes and shapes tend to vary, and so do sizes and shapes of root vegetables, plan on buying a bit extra of each vegetable to ensure that you will have enough to fill your baking dish.
- The main thing to keep in mind when selecting your produce is to try to pick vegetables with a similar width/diameter. This will ensure that your slices are as uniform as possible and will make your gratin presentation appear neater.
- A mandolin is the best tool to use for making sure your slices are an even thickness and will cook at the same rate.
- Keep the dish covered with foil for the first 30 minutes or so of baking, then remove it for the remainder of baking time so that when you add the cheese it gets nice and bubbly.
- Try playing around with different root vegetables in this dish, such as rutabagas, beets, or regular potatoes. In another version I added golden beets and it was lovely!
- Different cheeses such as raw cheddar, fontina or asiago would all work.
- If you want to lighten up this dish, you can replace up to half of the heavy cream with vegetable broth.
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Root Vegetable Gratin
- 3 ounces finely grated Gruyère
- 2 ounces finely grated Parmigiano-Reggiano
- 2 cups heavy cream
- 2 medium cloves garlic minced
- 1 tablespoon fresh thyme leaves roughly chopped (plus more for garnish)
- Salt and black pepper
- 4 pounds assorted root vegetables such as yams purple sweet potatoes and parsnips, peeled and sliced 1/8-inch thick on a mandoline
- 1/2 pound butternut squash neck only, peeled and sliced 1/8-inch thick on a mandoline
- 2 tablespoons unsalted butter
Heat oven to 400 degrees. Combine cheeses in a large bowl. Transfer 1/3 of cheese mixture to a separate small bowl and set aside. Add cream, garlic and thyme to the large bowl with cheeses. Season generously with salt and pepper.
Grease a 2-quart casserole dish with butter. Working in batches, pick up a stack of each type of vegetable about 2-3 inches thick and slices and toss in the cream mixture until every slice is well coated. Neatly stack and lay in the casserole dish with the edges aligned vertically. Continue placing vegetables in the dish, working around the perimeter and into the center until the dish is packed tightly. Pour remaining cream mixture evenly over the vegetables just until the mixture comes halfway up the sides of the casserole, and discard any that remains.
Cover dish tightly with foil and transfer to the oven. Bake for 30 minutes. Remove foil and continue baking until the top is pale golden brown, about 30 minutes longer. Remove from oven, sprinkle with remaining cheese, and return to oven. Bake until deep golden brown and crisp on top, about 30 minutes longer. Remove from oven, let rest for a few minutes, top with fresh thyme and serve.
Special Equipment: Mandoline