Description

This Cheesy Root Vegetable Gratin is a comforting and flavorful baked dish featuring thinly sliced sweet potatoes, parsnips, and beets layered with creamy Parmesan and Gruyere cheese, infused with fresh thyme and garlic. Perfect as a hearty side or a vegetarian main, it bakes to a golden, tender perfection that highlights the natural sweetness of the root vegetables.

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 & Cheese

14 tablespoons heavy cream, divided (whole milk can be used for a lighter dish)
4 ounces grated Parmesan, divided
1 ounce shredded Gruyere
1 tablespoon unsalted butter, softened (for greasing dish)

Herbs & Seasonings

1 tablespoon fresh minced thyme, divided (+ extra for garnish)
1 garlic clove, minced
Salt and pepper to taste

Cook Mode Prevent your screen from going dark

Instructions

Preheat Oven: Preheat your oven to 400°F (200°C). Grease a 3-quart baking dish with softened butter and set it aside to prepare for the gratin.
Slice Vegetables: Using a mandoline slicer, slice the sweet potatoes, parsnips, and beets into very thin rounds. Keep each vegetable type in its own separate bowl for easy seasoning.
Prepare Vegetables: Add 4 tablespoons of heavy cream to the sweet potato and parsnip bowls, and 2 tablespoons of cream to the beet bowl. Mix each with ½ ounce of grated Parmesan, 1 teaspoon of minced thyme, salt, and pepper. Toss each mixture thoroughly to coat every slice evenly.
Layer the Dish: Pour the remaining ¼ cup of cream into the prepared baking dish and sprinkle with ½ ounce of Parmesan and minced garlic. Begin layering the vegetables in rows: start with sweet potato, then parsnip, followed by beet, and repeat until all slices are used up.
Season and Bake: Sprinkle the top layer with the remaining Parmesan, and season with salt and pepper. Cover the baking dish with foil and bake in the preheated oven for 30 minutes.
Add Gruyere: After 30 minutes, remove the foil and sprinkle the shredded Gruyere cheese over the top. Continue baking uncovered for an additional 18-20 minutes, or until the vegetables are tender and the gratin is golden brown on top.
Finish and Serve: Garnish the gratin with fresh thyme leaves. Serve warm and enjoy the rich, cheesy layers alongside your favorite main dishes or as a satisfying vegetarian entrée.

Notes

Using a mandoline slicer ensures even, thin slices for uniform cooking.
Whole milk can be substituted for heavy cream to reduce richness.
Adjust the thyme quantity based on your preference for herb intensity.
Covering the dish during the first part of baking helps the vegetables cook through without drying out.
Gruyere adds a nutty, melty finish, but you can substitute with cheddar or fontina if preferred.

Prep Time: 20 minutes
Cook Time: 45 minutes
Category: Side Dish
Method: Baking
Cuisine: French-inspired