Cheesy Root Vegetable Gratin (Perfect Holiday Side Dish)

Root Vegetable Gratin

Layers of sweet potatoes, parsnips, and beets baked in cream with Parmesan and Gruyère for a stunning, cheesy holiday side dish that looks fancy but is surprisingly simple to make.

Prep Time: 15 minutes
Cook Time: 50 minutes
Total Time: 1 hour 5 minutes
Servings: 8

Ingredients

For the baking dish

• 1 tablespoon unsalted butter, softened (for greasing the dish)

For the 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 cream mixture & cheese

• 14 tablespoons heavy cream, divided
  • 4 tablespoons for sweet potatoes
  • 4 tablespoons for parsnips
  • 2 tablespoons for beets
  • 4 tablespoons (¼ cup) for the bottom of the dish
• 4 ounces grated Parmesan cheese, divided
• 1 tablespoon fresh thyme, minced, divided (plus extra for garnish)
• 1 garlic clove, minced
• 1 ounce shredded Gruyère cheese
• Salt and freshly ground black pepper, to taste

Step-by-Step Instructions

1. Prep the dish and oven
   • Preheat your oven to 400°F (200°C).
   • Grease a 3-quart baking dish generously with the softened butter, making sure to coat the sides and bottom.
2. Slice the vegetables
   • Using a mandoline (preferred for even thickness) or a very sharp knife, slice the sweet potatoes, parsnips, and beets into very thin rounds.
   • Keep each vegetable in its own separate bowl: one for sweet potatoes, one for parsnips, one for beets.
3. Season and cream the vegetables
   • To the sweet potato bowl, add 4 tablespoons heavy cream, ½ ounce grated Parmesan, and 1 teaspoon minced thyme. Season generously with salt and pepper and toss to coat every slice.
   • Repeat with the parsnips: 4 tablespoons heavy cream, ½ ounce Parmesan, 1 teaspoon thyme, plus salt and pepper. Toss well.
   • For the beets, add 2 tablespoons heavy cream, ½ ounce Parmesan, and 1 teaspoon thyme. Season and toss.
   • You want all slices coated, but especially with the beets, avoid drenching them in cream to help minimize color bleeding.
4. Cream and garlic base
   • Pour the remaining ¼ cup (4 tablespoons) heavy cream into the bottom of the greased baking dish.
   • Sprinkle with ½ ounce grated Parmesan and the minced garlic, distributing evenly across the base.
5. Arrange the vegetable rows
   • Grab a small stack of sweet potato slices, stand them up on a slight angle (bias), and place them at one end of the baking dish.
   • Next to that row, place a row of parsnip slices in the same manner.
   • Follow with a row of beet slices.
   • Continue alternating rows of sweet potato, parsnip, and beet until you’ve created about 6 rows and filled the dish. Pack them snugly so they stand upright and hold their shape.
6. Season and cover
   • Lightly season the top of the arranged vegetables with more salt and pepper.
   • Sprinkle the remaining Parmesan over the top.
   • Cover the dish tightly with foil, sealing around the edges to trap steam.
7. Bake until nearly tender
   • Place the covered dish in the oven and bake for 30 minutes, or until the vegetables are starting to soften when pierced with a knife but are not yet fully tender.
8. Add Gruyère and finish baking
   • Remove the foil and sprinkle the shredded Gruyère evenly over the top.
   • Return the dish to the oven, uncovered, and bake for another 18–20 minutes, or until:
     • The vegetables are fork-tender,
     • The cheese is fully melted, and
     • The top is lightly golden and bubbly.
9. Garnish and serve
   • Remove from the oven and let the gratin rest for about 5–10 minutes to allow the cream to thicken slightly.
   • Sprinkle with extra fresh thyme leaves.
   • Serve warm as a centerpiece side dish.

Pro Tips

• Keep slices even: Thin, uniform slices help the vegetables cook at the same rate and give the gratin its beautiful, layered look. A mandoline makes this faster and more consistent.
• Prevent beet bleeding: Coat beet slices lightly (not heavily) in cream and avoid too much cream pooling in the bottom of the dish. This helps keep the colors more distinct instead of everything turning pink.
• Make-ahead option: Assemble the gratin up to a day in advance, cover tightly with foil, and refrigerate. When ready to bake, place the covered dish in the oven and add about 5–7 extra minutes to the covered baking time. Note: the beets may bleed a bit more when made ahead, but the flavor will still be excellent.

Nutrition Info (Estimated)

Disclaimer: Nutrition facts are estimated using online tools and may vary based on your ingredients and preparation. Please consult a nutritionist for precise dietary advice.

Root Vegetable Gratin

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• Author: carlosramirez
• Total Time: 65
• Yield: 8 servings
• Diet: Vegetarian

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Description

Layers of sweet potatoes, parsnips, and beets baked in cream with Parmesan and Gruyère for a stunning, cheesy holiday side dish that looks fancy but is surprisingly simple to make.

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Ingredients

• 1 tablespoon unsalted butter, softened (for greasing the dish)
• 1–2 long sweet potatoes (about 2 inches thick), peeled
• 3–4 large parsnips, ends trimmed and peeled
• 3–5 small beets, peeled
• 14 tablespoons heavy cream, divided
• 4 ounces grated Parmesan cheese, divided
• 1 tablespoon fresh thyme, minced, divided (plus extra for garnish)
• 1 garlic clove, minced
• 1 ounce shredded Gruyère cheese
• Salt and freshly ground black pepper, to taste

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Instructions

1. Preheat your oven to 400°F (200°C).
2. Grease a 3-quart baking dish generously with the softened butter, coating the sides and bottom.
3. Using a mandoline or sharp knife, slice the sweet potatoes, parsnips, and beets into very thin rounds and keep each vegetable in its own bowl.
4. To the sweet potato bowl, add 4 tablespoons heavy cream, ½ ounce Parmesan, and 1 teaspoon thyme. Season with salt and pepper and toss to coat.
5. Repeat with the parsnips and beets, using their respective amounts of cream, cheese, and thyme.
6. Pour the remaining ¼ cup (4 tablespoons) heavy cream into the bottom of the greased baking dish and sprinkle with ½ ounce Parmesan and the minced garlic.
7. Arrange the vegetable rows in the dish, alternating between sweet potato, parsnip, and beet slices until filled, packing them snugly to stand upright.
8. Season the top with salt and pepper and sprinkle with remaining Parmesan. Cover tightly with foil.
9. Bake covered for 30 minutes until vegetables are starting to soften.
10. Remove the foil and sprinkle the shredded Gruyère on top. Bake uncovered for another 18-20 minutes until fork-tender and lightly golden.
11. Let the gratin rest for 5-10 minutes, sprinkle with extra thyme leaves, and serve warm.

Notes

Keep slices even for best results and prevent beet bleeding by not using too much cream. The gratin can be assembled a day in advance.

• Prep Time: 15
• Cook Time: 50
• Category: Side Dish
• Method: Baking
• Cuisine: American