Description

This Cheesy Root Vegetable Gratin is a comforting and elegant dish featuring thinly sliced sweet potatoes, parsnips, and beets layered with creamy Parmesan and Gruyere cheese. Baked to golden perfection, it’s a perfect side for cozy dinners or holiday meals, offering a rich blend of earthy flavors and creamy textures.

Ingredients

Scale

Vegetables

1–2 long sweet potatoes (about 2 inches thick), peeled
3–4 large parsnips, ends trimmed and peeled
3–5 small beets, peeled

For the Gratin

1 tablespoon unsalted butter (softened), for greasing
14 tablespoons heavy cream, divided (whole milk can be used but will be less creamy)
4 ounces grated Parmesan cheese, divided
1 tablespoon fresh minced thyme, divided (plus more for garnish)
1 garlic clove, minced
1 ounce shredded Gruyere cheese
Salt and pepper to taste

Instructions

Prepare the Oven and Dish: Preheat your oven to 400˚F. Grease a 3-quart (preferably oval) baking dish with softened butter to prevent sticking and add flavor.
Slice the Vegetables: Using a mandoline or a sharp knife, slice sweet potatoes, parsnips, and beets into very thin rounds. Place each type of sliced vegetable into separate bowls.
Season the Vegetables: Pour 4 tablespoons of heavy cream over the sweet potatoes and parsnips, and 2 tablespoons over the beets. Add ½ ounce grated Parmesan and 1 teaspoon minced thyme to each bowl. Generously season each with salt and pepper, then toss well so all slices are evenly coated.
Prepare the Baking Dish Base: Pour the remaining ¼ cup of heavy cream into the bottom of the prepared baking dish. Sprinkle with ½ ounce of Parmesan and the minced garlic to build a flavorful base layer.
Arrange the Vegetables: Starting with sweet potatoes, stand the slices upright on a diagonal at the top of the baking dish in a row. Next, create a row of parsnips, followed by a row of beets. Repeat this layering with remaining vegetables until you create six rows total, packed closely together.
Season and Cover: Sprinkle salt, pepper, and the remaining Parmesan cheese evenly on top of the arranged vegetables. Cover the dish tightly with aluminum foil to trap moisture and cook evenly.
Bake Covered: Place the gratin in the oven and bake for 30 minutes, or until the vegetables start to become tender.
Add Gruyere and Bake Uncovered: Remove the foil and evenly sprinkle the shredded Gruyere cheese over the vegetables. Return the dish to the oven uncovered and bake for an additional 18 to 20 minutes until the vegetables are fork tender, the cheese has melted, and the top is lightly browned.
Finish and Serve: Remove from the oven, sprinkle fresh thyme leaves over the top for a burst of herbaceous flavor, and serve warm as a delicious side dish.

Notes

Using a mandoline helps achieve very thin, even slices for uniform cooking.
Whole milk can substitute for heavy cream but expect a less creamy texture and thinner sauce.
Beets tend to cook slightly slower; slicing thinly and layering properly helps even cooking.
Covering the dish while baking helps steam and soften the vegetables before browning.
Gruyere cheese adds a nutty, melty topping that complements the Parmesan base nicely.
Leftovers can be refrigerated for up to 3 days and reheated gently in the oven.

Prep Time: 20 minutes
Cook Time: 45 minutes
Category: Side Dish
Method: Baking
Cuisine: American

Keywords: Cheesy gratin, root vegetable gratin, sweet potato gratin, parsnip recipe, beet gratin, baked vegetable casserole, vegetarian side dish