Description
A creamy and cheesy Sweet Potato Gratin featuring layers of red-skinned sweet potatoes and Yukon Gold potatoes baked in a fragrant mixture of half-and-half, garlic, thyme, and Gruyère and Parmesan cheeses. This comforting dish is perfect as a hearty side for dinners or holiday meals, offering a perfect balance of sweet and savory flavors baked to golden perfection.
Ingredients
Potatoes
- 1 ½ pounds red-skinned sweet potatoes
- 1 pound Yukon Gold potatoes
Dairy & Fats
- 1 ½ cups half-and-half
- 1 ½ tablespoons butter (divided)
- 1 ½ cups shredded Gruyère cheese
- ¼ cup finely shredded Parmesan cheese
Seasonings & Herbs
- 1 teaspoon minced garlic
- 1 tablespoon chopped fresh thyme
- ½ teaspoon fine ground sea salt (or to taste)
- Freshly ground black pepper (to taste)
Instructions
- Slice Potatoes: Peel the sweet potatoes and Yukon Gold potatoes, then slice them into ⅛-inch thick rounds using a mandoline or the slicing blade on a food processor for uniform thickness.
- Prepare Cream Mixture: Combine half-and-half, 1 tablespoon of butter, and minced garlic in a small saucepan and warm over low heat. Take care not to let the mixture boil over as you prepare the rest of the dish.
- Preheat Oven & Prepare Dish: Preheat your oven to 400°F (204°C). Butter a 12-inch enameled or regular cast iron pan (or a similar sized gratin dish) using the remaining ½ tablespoon of butter to prevent sticking.
- Layer First Half: Place half of the potato slices in the baking dish, alternating sweet potato and Yukon Gold slices. Season evenly with half the salt, freshly ground black pepper to taste, and half the chopped fresh thyme. Sprinkle half of both the Gruyère and Parmesan cheese evenly over the layer.
- Layer Second Half: Repeat the layering process with the remaining potatoes, salt, pepper, thyme, and cheeses. Press the layers gently by hand to compact them in the baking dish, then pour the warmed half-and-half and butter mixture over the top evenly.
- Bake Covered: Cover the dish (a foil cover or tightly fitting lid works) and bake for 40 minutes to allow the potatoes to begin cooking and absorb flavors.
- Bake Uncovered: Remove the cover and continue baking for an additional 15 minutes or until the top is golden brown, the potatoes are fork tender, and most of the liquid has been absorbed.
- Rest Before Serving: Let the gratin rest for 5 to 10 minutes once out of the oven to allow it to set and make serving easier. Serve warm as a delicious side dish.
Notes
- Covering the gratin during the initial baking helps cook the potatoes thoroughly while preventing the top from browning too quickly.
- For an even crispier top, you can broil the gratin for 1-2 minutes at the end of baking, watching carefully to avoid burning.
- If you do not have fresh thyme available, dried thyme can be substituted, though use about 1 teaspoon as dried herbs are more concentrated.
- This recipe can be prepared a few hours ahead; after baking, cool completely, cover, and refrigerate. Reheat covered at 350°F (175°C) until warmed through.
- Prep Time: 20 minutes
- Cook Time: 55 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: French
