Root Vegetable Gratin with Sweet Potatoes, Parsnips, and Beets

There’s something wonderfully comforting about a bubbling vegetable gratin coming out of the oven. This Root Vegetable Gratin combines sweet potatoes, earthy beets, and tender parsnips in beautiful layers, all covered in a creamy garlic sauce and topped with golden, melted cheese.

I love how this dish brings simple root vegetables together in such an elegant way. The sweet potatoes add natural sweetness, the parsnips bring a delicate earthy flavor, and the beets give the gratin a gorgeous color. It’s perfect for a cozy family dinner, a holiday table, or any evening when you want a hearty vegetable side dish that feels a little special.

Why You’ll Love This Recipe

• Comforting and creamy: A rich garlic cream sauce coats every layer.
• Beautiful colors: Orange sweet potatoes, golden parsnips, and ruby-red beets make an eye-catching dish.
• Perfect for gatherings: An elegant side for holiday dinners and family meals.
• Flexible ingredients: Easily adapt the cheese, herbs, and seasonings to your taste.

Ingredients

• 2 medium sweet potatoes, peeled
• 2 medium parsnips, peeled
• 2 medium beets, peeled
• 1 cup heavy cream
• ½ cup milk
• 2 garlic cloves, minced
• 1 cup shredded Gruyère or sharp cheddar cheese
• ¼ cup grated Parmesan cheese
• 1 tablespoon butter, for greasing the baking dish
• 1 teaspoon fresh thyme leaves, or ½ teaspoon dried thyme
• ½ teaspoon salt, or to taste
• ¼ teaspoon black pepper
• Pinch of ground nutmeg, optional
• 1 tablespoon chopped fresh parsley, for garnish

Instructions

Step 1: Prepare the Vegetables

Preheat the oven to 375°F (190°C). Grease a medium baking dish with butter. Slice the sweet potatoes, parsnips, and beets into thin, even rounds, approximately ⅛ inch thick. A mandoline can help create uniform slices; use its safety guard.

Step 2: Make the Creamy Garlic Sauce

In a bowl, whisk together the heavy cream, milk, minced garlic, thyme, salt, black pepper, and optional nutmeg. Stir until the seasonings are evenly distributed.

Step 3: Layer the Vegetables

Arrange the sweet potato, parsnip, and beet slices in overlapping layers in the baking dish. You can alternate the vegetables for a colorful presentation or create separate rows of each vegetable.

Step 4: Add the Cream Sauce

Pour the garlic cream mixture evenly over the vegetables. Gently press the layers down so the sauce reaches between the slices.

Step 5: Bake Until Tender

Cover the dish with foil and bake for 40–45 minutes. Remove the foil and carefully test the vegetables with a knife. If they are still firm, continue baking until nearly tender.

Step 6: Add the Cheese

Sprinkle the Gruyère or cheddar and Parmesan evenly over the top. Return the dish to the oven, uncovered, for another 20–25 minutes, until the vegetables are tender and the cheese is golden and bubbling.

If the top browns too quickly, loosely cover it with foil.

Step 7: Rest and Serve

Let the gratin rest for 10 minutes before serving. This allows the creamy sauce to settle and makes the layers easier to serve. Finish with fresh parsley if desired.

Tips for the Best Root Vegetable Gratin

• Slice evenly: Uniform slices help all the vegetables cook at the same rate.
• Use separate cutting boards: Beets can stain other vegetables and kitchen surfaces.
• Don’t rush the baking: Root vegetables need enough time to become tender all the way through.
• Choose flavorful cheese: Gruyère gives a nutty flavor, while sharp cheddar adds a richer, familiar taste.
• Allow it to rest: The sauce thickens slightly as the gratin cools.

Easy Variations

• Herb-infused gratin: Add fresh rosemary or sage along with the thyme.
• Extra cheesy: Add a little mozzarella for a stretchier cheese topping.
• Lighter version: Replace some of the heavy cream with additional milk, keeping in mind that the sauce will be less rich.
• Vegan gratin: Use unsweetened plant-based milk, dairy-free cream, olive oil, and a suitable vegan cheese.
• Crispy topping: Sprinkle a small amount of seasoned breadcrumbs over the cheese before the final bake.

What to Serve with Root Vegetable Gratin

This gratin pairs beautifully with roast chicken, baked salmon, grilled pork chops, roasted turkey, or a hearty lentil dish. For a vegetarian meal, serve it with a fresh green salad and crusty whole-grain bread.

It also makes a lovely holiday side dish alongside roasted vegetables and seasonal greens.

Make-Ahead and Storage

You can slice the vegetables and prepare the cream mixture a few hours ahead. Keep the sliced vegetables covered in the refrigerator and assemble the gratin shortly before baking for the best texture.

Alternatively, assemble the dish, cover it, and refrigerate for up to 24 hours before baking. Because it will start cold, allow extra baking time and check that the center is hot and the vegetables are tender.

Store leftovers in an airtight container in the refrigerator for 3–4 days. Reheat covered in a 350°F (175°C) oven until heated through. Avoid leaving the gratin at room temperature for more than 2 hours.

Recipe Details

• Prep Time: 25 minutes
• Cook Time: 65–75 minutes
• Rest Time: 10 minutes
• Total Time: About 1 hour 45 minutes
• Servings: 6
• Difficulty: Moderate

Approximate Nutrition Per Serving

• Calories: 330
• Protein: 10 g
• Carbohydrates: 31 g
• Fat: 20 g
• Fiber: 5 g
• Sugar: 10 g

Nutrition estimates vary depending on vegetable sizes, cream, and cheese used.

Frequently Asked Questions

1. Do I need to cook the root vegetables before layering them?

No. Thinly sliced raw vegetables can be baked directly in the cream sauce. Covering the dish during the first part of baking helps them soften.

2. Can I make this gratin without beets?

Yes! Replace the beets with extra parsnips, carrots, or thinly sliced Yukon Gold potatoes. The flavor and color will change slightly, but the gratin will still be delicious.

3. How can I tell when the gratin is ready?

Insert a thin knife into the center. It should slide through the thickest vegetable slices easily, and the sauce should be bubbling around the edges.

4. Can I freeze root vegetable gratin?

You can freeze it, but cream-based sauces may separate and the vegetables may soften after thawing. For the best texture, refrigerate leftovers and enjoy them within a few days.