Description

This Cheesy Root Vegetable Gratin is a delightful and colorful baked dish combining thinly sliced sweet potatoes, parsnips, and beets layered vertically in a creamy, cheesy sauce infused with thyme and garlic. Perfect as a comforting side dish or a vegetarian main, it bakes to a golden, bubbly finish that highlights the natural sweetness of the root vegetables paired with rich Gruyere and Parmesan cheeses.

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

Dairy & Seasonings

1 tablespoon unsalted butter (softened), plus extra for greasing
14 tablespoons heavy cream, divided
4 ounces grated Parmesan cheese, divided
1 ounce shredded Gruyere cheese
1 tablespoon fresh minced thyme, divided plus extra for garnish
1 garlic clove, minced
Salt and freshly ground black pepper, to taste

Instructions

Preheat and prepare baking dish: Preheat your oven to 400˚F (200˚C). Grease a 3-quart baking dish with softened unsalted butter to prevent sticking and add a touch of richness to the gratin.
Slice the vegetables: Using a mandoline slicer, carefully thinly slice the sweet potatoes, parsnips, and beets. Keep the slices separate by placing each vegetable into its own bowl to make seasoning easier later.
Season the vegetables: To each bowl of sliced vegetables, add 4 tablespoons of heavy cream, half an ounce of grated Parmesan cheese, a portion of the fresh minced thyme, salt, and freshly ground black pepper. Toss each vegetable thoroughly so that the slices are evenly coated with the cream and seasoning.
Prepare the base of the gratin: Pour the remaining 1/4 cup (4 tablespoons) of heavy cream into the bottom of the greased baking dish. Sprinkle the minced garlic evenly over the cream layer to infuse flavor into the dish.
Layer the vegetables: Arrange the vegetables vertically in the dish in neat rows starting with the sweet potatoes, then the parsnips, and finally the beets. This layering keeps the colors distinct and creates an attractive visual effect when baked.
Add remaining seasonings and cheese: Sprinkle the rest of the Parmesan cheese and the remaining thyme evenly over the layered vegetables. Finally, top the arrangement with shredded Gruyere cheese which will melt and brown beautifully during baking.
Bake with foil cover: Cover the baking dish tightly with aluminum foil to keep moisture in and bake in the preheated oven for 30 minutes. This initial baking steams the vegetables and melts the cheese gently.
Bake uncovered to brown: Remove the foil and continue to bake for an additional 20 minutes or until the top is golden brown and bubbly. This step develops a rich crust and caramelizes the cheese.

Notes

Using a mandoline ensures uniform thin slices for even cooking.
Make sure to peel the beets carefully to avoid staining hands; wearing gloves is recommended.
Substitute Gruyere with Swiss or Fontina cheese if unavailable.
This gratin pairs beautifully with roasted meats or can be served as a hearty vegetarian entrée.
Leftovers reheat well in the oven at a low temperature to maintain crispness.

Prep Time: 20 minutes
Cook Time: 50 minutes
Category: Side Dish
Method: Baking
Cuisine: French

Keywords: root vegetable gratin, cheesy gratin, sweet potato parsnip beet gratin, vegetarian side dish, baked root vegetables, Gruyere cheese dish