Sweet Potatoes au Gratin

This sweet potato gratin stands out from the typical gratin with sweet potatoes instead of the usual white or russet potatoes. Sweet potatoes add a unique natural sweetness and a vibrant color to the dish, which pairs beautifully with the rich cream sauce. Unlike traditional gratins that often rely on a combination of cheeses, this recipe focuses on the savory tang of Parmesan cheese, which contrasts nicely with the sweet potatos flavor. Perfect for pairing with roasted meats or a hearty salad, this gratin recipe is not only delicious but also simple to prepare, making it an easy go-to recipe for impressing your guests with minimal effort.

Ingredients for Sweet Potato Gratin

• Sweet potatoes: Rich in vitamins A and C, sweet potatoes provide a natural sweetness, vibrant color and tender texture making them a delicious and nutritious alternative to traditional potatoes.
• Egg: The egg helps to bind the ingredients together, creating a cohesive texture in the gratin.
• Heavy whipping cream: Use full-fat heavy whipping cream or heavy cream for the creamiest sauce.
• Salt: A sprinkle of salt enhances the natural sweetness of the sweet potatoes and balances the flavors in the creamy sauce.
• Ground nutmeg: The warm, slightly sweet flavor of nutmeg adds a subtle warmth and aromatic depth that’s a perfect partner with sweet potatoes.
• Pepper: A dash of fresh black pepper is a simple way to add extra seasoning.
• Grated Parmesan cheese: This savory, umami-rich cheese adds a slightly crispy, golden-brown topping when baked.
• Fresh thyme (optional): Top this dish with some fresh thyme for a pop of color and a fragrant, herbaceous endnote.

Directions

Step 1: Prepare the ingredients

Place potatoes in a greased 8 inch square baking dish. Beat the egg in a bowl. Add  cream, salt, nutmeg and pepper and mix it well. Pour over the potatoes and sprinkle with Parmesan cheese.

Step 2: Bake and serve

Bake, uncovered, at 375°F until the potatoes are tender, for 40 to 45 minutes. If desired, top with fresh thyme to serve.

Editor’s Tip: If the top starts to brown too quickly, cover the gratin with foil during the latter part of baking to prevent burning while allowing the potatoes to cook through.

Recipe Variations

• Make it extra cheesy: Add a blend of shredded Gruyère and cheddar cheese to the cream mixture for an extra cheesy and rich gratin.
• Add bacon: Sprinkle cooked, crumbled bacon between the layers of sweet potatoes for a smoky, savory addition.
• Go nutty: Top the gratin with a mixture of chopped pecans or walnuts and breadcrumbs for a crunchy, nutty finish.
• Create a vegan version: Substitute heavy cream with coconut milk or cashew cream and use a dairy-free cheese alternative for a vegan-friendly version.

How to Store Sweet Potato Gratin

To store sweet potato gratin let it cool to room temperature then cover it tightly with plastic wrap or aluminum foil or transfer it to an airtight container. Store it in the refrigerator for three to four days. When ready to reheat, warm it in a 350° oven until heated through.

Can you freeze sweet potato gratin?

Freezing gratins is generally not recommended because it can cause the sweet potatoes to become mushy and the cream sauce to separate or become grainy. This will lead to a less desirable consistency and flavor when reheated.

Can you make sweet potato gratin ahead of time?

Yes, you can make sweet potato gratin ahead of time. Prepare the dish as instructed but stop just before baking. Cover the assembled gratin tightly with plastic wrap or aluminum foil and store it in the refrigerator for up to 24 hours. When ready to serve, remove the covering and bake as directed, adding a few extra minutes to ensure it is heated.

Sweet Potato Gratin Tips

Can I use different potatoes?

Yes, you can use different types of potatoes in this sweet potato gratin. Mixing sweet potatoes with other varieties, such as Yukon Gold, russet or even red potatoes can add a unique flavor and texture. This combination creates a delightful contrast between the natural sweetness of the sweet potatoes and the more starchy, savory flavors of the other potatoes.

How do I prevent the cream from curdling?

To prevent the cream from curdling in your sweet potato gratin, use fresh, high-quality heavy whipping cream. An older cream that might have been sitting in your fridge for a few days is more prone to curdling. Whisk the egg and cream mixture thoroughly to ensure a smooth consistency before pouring it over the potatoes. Bake the gratin at a moderate temperature, like the recommended 375° to avoid overheating the cream too quickly. If your oven tends to run hot, consider covering the dish with foil for the first part of the baking time and uncover it to allow for browning, which helps the cream heat gradually. Additionally, adding a small amount of flour or cornstarch to the cream mixture can stabilize the emulsion and prevent curdling.

What do you serve with sweet potato gratin?

Sweet potato gratin pairs beautifully with roasted meats such as chicken, turkey, pork tenderloin or beef roast, as the savory flavors of the meat balance the sweetness of the potatoes. Light and flaky grilled fish like salmon or cod provide a nice contrast to the rich and creamy gratin. Green vegetables such as steamed broccoli, green beans, asparagus or Brussels sprouts add a fresh, crunchy element while a crisp garden salad with a light vinaigrette offers a refreshing contrast.