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Root vegetable gratin

Cheesy Root Vegetable Gratin: A Stunning Holiday Side Dish

This cheesy root vegetable gratin transforms humble winter vegetables into a show-stopping holiday side dish. Layers of thinly sliced sweet potatoes, parsnips, and beets bake in a garlic-thyme cream sauce and finish under a golden, melty Gruyère topping. Elegant, flavorful, and surprisingly simple to prepare!
Prep Time 30 minutes
Cook Time 50 minutes
Total Time 1 hour 25 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American, Holiday
Calories: 245

Ingredients
  

  • 1–2 long sweet potatoes, peeled
  • 3–4 large parsnips, peeled and trimmed
  • 3–5 small beets, peeled
  • 1 tablespoon unsalted butter, for greasing
  • 14 tablespoons heavy cream, divided
  • 4 ounces grated Parmesan cheese, divided
  • 1 tablespoon fresh minced thyme, divided
  • 1 clove garlic, minced
  • 1 ounce shredded Gruyère cheese
  • Salt and black pepper to taste

Equipment

  • Mandoline slicer or sharp knife
  • 3-quart baking dish
  • Mixing bowls (3)
  • Vegetable peeler
  • Aluminum foil
  • Kitchen gloves (for beets)

Method
 

  1. Preheat oven to 400°F. Grease a 3-quart baking dish generously with butter. Use a mandoline or sharp knife to slice sweet potatoes, parsnips, and beets into 1/8-inch rounds. Place each vegetable in its own mixing bowl.
  2. Pour 4 tablespoons heavy cream over the sweet potatoes and 4 tablespoons over the parsnips. Add 2 tablespoons cream to the beets (to reduce bleeding). Add 1/2 ounce Parmesan and 1 teaspoon thyme to each bowl. Season each with salt and pepper, then toss gently to coat.
  3. Pour the remaining 1/4 cup cream into the bottom of the baking dish. Sprinkle with 1/2 ounce Parmesan and the minced garlic. Arrange vegetables in rows, standing upright on a slight angle, alternating sweet potato, parsnip, and beet slices. Continue until the dish is filled.
  4. Season the top with salt, pepper, and remaining Parmesan. Cover tightly with aluminum foil and bake for 30 minutes until vegetables are beginning to soften.
  5. Remove foil. Sprinkle Gruyère evenly over top. Return to oven and bake uncovered for 18–20 minutes, or until vegetables are fully tender and cheese is golden brown.
  6. Let rest 5 minutes before serving. Garnish with additional thyme if desired.

Notes

For best color separation, use less cream on the beets and avoid a thick cream layer at the bottom. Uniform slicing ensures even cooking.

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