Sweet Potato Gratin

4.67 from 3 votes

This heavenly, garlic-infused Sweet Potato Gratin is a delicious choice for the holidays. Thinly sliced sweet potatoes and buttery Yukon gold potatoes are layered with Gruyère and Parmesan cheese and baked until golden brown.

Prep Time15

Cook Time50

Total Time1 5

Course: Side Dish

Cuisine: American, French

Servings:

Calories: 419kcal

Author: Valerie Brunmeier

Ingredients

1 ½ pounds red-skinned sweet potatoes
1 pound Yukon Gold potatoes
1 ½ cups half-and-half
1 ½ tablespoons butter divided
1 teaspoon minced garlic
1 tablespoon chopped fresh thyme
½ teaspoon fine ground sea salt or to taste
freshly ground black pepper to taste
1 ½ cup shredded Gruyère cheese
¼ cup finely shredded Parmesan cheese

Instructions

Peel the sweet potatoes and Yukon Gold potatoes and use a mandoline or the slicing blade on a food processor to slice them into ⅛-inch thick rounds.
Combine the half-and-half, 1 tablespoon butter, and garlic in a small saucepan and place over LOW heat. Watch the pot to be sure it doesn’t boil over while you proceed with the rest of the recipe.
Preheat oven to 400 degrees F. Butter a 12-inch enameled (or regular) cast iron pan (or similar sized gratin dish) with the remaining ½ tablespoon of butter.
Transfer half of the potatoes to the prepared baking dish, arranging them so that you are alternating the sweet potato slices with some Yukon Gold potato slices. Sprinkle with half of the salt, pepper to taste, and half of the fresh thyme. Sprinkle half of the Gruyère and Parmesan cheese evenly over the top.
Repeat layering with remaining potatoes, salt, pepper, thyme, and cheeses. Use your hands to compact the mixture down into the baking dish and then pour the half-and-half mixture over the top.
Cover (*see note below) and bake for 40 minutes. Remove the cover and continue to bake for an additional 15 minutes or until the top of the gratin is golden, the potatoes are fork tender, and most of the liquid is absorbed. Let it rest for 5 to 10 minutes before serving.

Notes

* If you’re using a baking dish or pan without a lid, cut off a sheet of foil large enough to cover your dish and coat the bottom side with nonstick cooking spray. This will ensure the cheese will not stick to the foil when you remove it.

Make Ahead Instructions:

This dish can be assembled up to 6 hours ahead of time. Just cover it with plastic wrap and refrigerate. Remove it from the refrigerator about 30 minutes before baking to take the chill off. Remove the plastic wrap and proceed as directed.

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