Sweet Potato Gratin
This Sweet Potato Gratin is a show-stopping side dish for any holiday! Thinly sliced sweet potatoes bake in a creamy herbed garlic sauce with nutty Gruyère and Parmesan until tender and golden. Irresistible crispy edges guaranteed!
Give sweet potatoes a savory spin with this gratin recipe!
Sweet potatoes usually show up on the Thanksgiving table with lots of brown sugar, cinnamon, and marshmallows. Personally, I love taking them in a more savory direction.
Here, the earthy sweetness of sweet potatoes is balanced by garlic, fresh thyme, and plenty of cheese.
While my family will always demand my Sweet Potato Casserole every Thanksgiving, this sweet potato gratin is going on the table this year right next to it!
Ingredients and Substitutions
You’ll find the full list of ingredients in the recipe card below, but here are some notes to keep in mind.
- Unsalted Butter. Let the butter soften so it’s easy to spread into the bottom of the pan.
- Sweet Potatoes. While you can absolutely make this gratin with regular orange sweet potatoes, using a mix of orange, purple, and white varieties turns it into a showstopper. Choose potatoes that are relatively similar in diameter so the slices fit together neatly.
- Heavy Cream. You can use a combination of heavy cream and half-and-half for a somewhat lighter version, although the finished sauce will be less rich and creamy. (I say, if it’s a holiday—go all out!)
- Fresh Thyme. Thyme is a lovely pairing with sweet potatoes, but if you’d like to take this in a different direction, try rosemary or sage.
- Garlic. For savory flavor.
- Ground Nutmeg. Adds a little warmth rather than making the dish taste sweet.
- Gruyère Cheese. One of my favorite cheeses for a gratin. It melts beautifully and has a nutty, slightly sweet flavor. Some melts into the sauce, while the rest goes between and over the potato slices.
- Parmesan Cheese. A savory, umami complement to the Gruyère and the sweet potatoes.
Step-By-Step Instructions
Prepare the Skillet. Place a rack in the center of your oven and preheat to 375 degrees F. Rub the butter all over the inside of a cast iron skillet or baking dish.
Slice the Sweet Potatoes. Scrub and peel the sweet potatoes. Slice them into 1/8-inch-thick rounds. A mandoline is the easiest way to get slices that are consistently thin, which is important for even cooking.
Arrange the Sweet Potatoes. Starting at the outer edge of the skillet, stand the sweet potato slices upright on their edges. Shingle them around the perimeter, overlapping the slices slightly like fallen dominoes. Once you’ve completed the outer ring, begin another ring inside it. Continue until the skillet is full.
Warm the Cream. In a small saucepan, combine the heavy cream, thyme, garlic, and seasonings. Warm over medium heat, whisking frequently, until the cream begins to steam. (Don’t let it boil!) Remove the saucepan from the heat. Stir in 1/4 cup Gruyère and 1/4 cup Parmesan.
Assemble. Sprinkle 1/4 cup Gruyère over the arranged sweet potatoes. Slowly pour the warm cream mixture over the potatoes, moving around the entire skillet so the liquid reaches all the slices. Sprinkle the remaining cheese over the top.
Bake Covered. Cover the skillet tightly with foil. Bake for 35 minutes. During this first stage, the trapped steam helps soften the sweet potatoes.
Uncover and Brown. Remove the foil. Return the gratin to the oven and bake for another 18 to 20 minutes. The sweet potatoes should be tender, the cream should have thickened, and the edges should be golden. If you’d like a more browned top, place the skillet under the broiler for a minute or two.
Let It Rest. Remove the gratin from the oven and sprinkle with additional fresh thyme. Let it rest for 10 minutes before serving. ENJOY!
Erin’s Testing Notes
It’s absolutely critical that you shred your own cheese for this recipe. I know Trader Joe’s sells shredded Gruyère, but resist the temptation! Store-bought shredded cheese is coated in an anti-caking agent, which gives cheese sauces a slightly mealy texture. Grate both the Gruyère and the Parmesan from the block for the best texture and flavor. I promise, it is worth it!
What to Serve with Sweet Potato Gratin
- Holiday Mains. Sweet potato gratin is perfection alongside Spatchcock Turkey for Thanksgiving, or serve it with my Standing Rib Roast Recipe or Crockpot Ham for other holiday celebrations.
- Other Holiday Sides. This Healthy Green Bean Casserole is a reader favorite! At my Thanksgiving, we always serve this Cornbread Stuffing Recipe and tangy Cranberry Orange Relish too.
Sweet Potato Gratin
Ingredients
- 1 tablespoon unsalted butter softened
- 2 ½ pounds sweet potatoes; I used a mix of orange, purple, and white
- 1 ½ cups heavy cream or a mix of heavy cream and half-and-half
- 2 teaspoons fresh thyme leaves plus additional for serving
- 2 garlic cloves minced
- 1 ½ teaspoons kosher salt
- ¼ teaspoon ground nutmeg
- ¼ ground black pepper
- ¾ cup shredded Gruyère cheese divided
- ¼ cup plus 2 tablespoons grated Parmesan divided
Instructions
- Preheat the oven to 375°F. Rub the butter all over the inside of a 10-inch cast iron skillet, or similarly sized dish.
- Scrub and peel the sweet potatoes. Slice into 1/8-inch thick rounds (a mandoline is the best way to do this). If you are using different colors, keep the colors separate.
- Starting at the outer edge of the skillet, stand the slices up on their edges, then shingle them around the perimeter of the pan like fallen dominoes to create a ring (if using different colors, add the sweet potatoes in alternating color blocks). Repeat, adding another ring inside the first. Continue until the skillet is full.
- In a small saucepan, warm the cream with the thyme, garlic, salt, nutmeg, and pepper. Heat until the cream steams and small bubbles form all around the edges, whisking often. Remove from the heat and stir in ¼ cup Gruyère and ¼ cup Parmesan.
- Sprinkle the potatoes with ¼ cup Gruyère, then pour the cream mixture over the top, drizzling it slowly and evenly over the surface area. Top with the remaining ¼ cup Gruyère and 2 tablespoons Parmesan.
- Cover the pan tightly with foil and bake 35 minutes. Uncover, then bake 18 to 20 minutes more, until the sweet potatoes are fork-tender, the cream has thickened, and the top is golden and crisp at the edges. If desired, pop the pan under the broiler for a few minutes to further brown the cheese.
- Sprinkle with additional fresh thyme. Let the gratin rest 10 minutes before serving.
Notes
- TO STORE: Refrigerate leftover Sweet Potato Gratin in an airtight container for up to 4 days. (I don’t recommend freezing this gratin. Cream-based sauces can separate after thawing, and the sweet potatoes may become mushy.)
- TO REHEAT: Cover with foil and warm in a 350°F oven until heated through. Remove the foil toward the end if you’d like to crisp the top again.
Nutrition
from Well Plated by Erin Clarke https://ift.tt/GOt6gNs
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