Sweet Potato Gratin with Gruyere & Caramelized Shallots Recipe

by: Kate McMillan

Cook Time | 1 hour 45 minutes
Prep Time | 30 minutes
Yield | 8 servings

Summary

This incredibly flavorful and stunning dish is a perfect side at Thanksgiving, but it’s also hearty enough to satisfy as a vegetarian entree. Layers of sweet potatoes, thyme-infused cream and two kinds of cheese make it pretty irresistible. We went one step further and added caramelized shallots for a show-stopper of a recipe.

Ingredients

2 tablespoons extra-virgin olive oil
6 shallots, halved and sliced
Kosher salt
Freshly ground black pepper
1 cup whole milk
1 cup heavy cream
2 tablespoons unsalted butter
2 tablespoons plus 1 teaspoon fresh thyme, divided
3 sweet potatoes
1½ cups shredded Gruyere cheese
¼ cup grated Parmesan cheese

Directions

Warm the olive oil in a skillet over medium-high heat. Add the shallots and season with salt and pepper. Saute, stirring occasionally, until the shallots soften, about 6 minutes. Reduce heat to low and continue to saute, stirring occasionally, until shallots are dark golden brown, about 40 minutes. Set aside.
Preheat the oven to 400°F. Lightly coat a large Staub 11-inch oval baker with non-stick cooking spray and set aside.
Add the milk, heavy cream, butter and 2 tablespoons of thyme to a saucepan and set over medium heat. Warm just until the butter is completely melted and stir to combine. Set aside.
Peel sweet potatoes and, using the slicing attachment on a food processor, cut into ⅛-inch slices. Add half of the sweet potatoes to the prepared pan and sprinkle half of the caramelized onions over the top. Pour all of the warmed milk over the top. Sprinkle with half of the Gruyere and Parmesan cheeses. Top with the remaining sweet potato slices and cheeses and season with salt and pepper. Finish with the remaining caramelized shallots as well as the remaining ½ teaspoon thyme leaves.
Cover the pan with aluminum foil and transfer to the oven. Bake for 30 minutes, remove the cover and continue to bake until golden brown and bubbly, about 30 minutes more. Cool for 10 minutes and serve.

Notes

If you don’t have a food processor, you can use a mandoline or a very sharp knife.

The shallots can be caramelized up to 2 days in advance and stored in the refrigerator.

If you want to make this sweet potato gratin with gruyere and caramelized shallots recipe ahead of time, bake for the first 30 minutes, cool completely and store in the refrigerator. Then cook the second 30 minutes the day you are serving.