Sweet Potato Gratin

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Sweet potato gratin is layers of sweet potato, butternut squash and potatoes are baked in a creamy cheese sauce.

Prep Time20

Cook Time40

Course: Side Dish

Cuisine: American

Servings: servings

Calories: 188kcal

Author: Cynthia

2 Tablespoon unsalted butter
2 ounces pancetta
1 medium shallot sliced, about 1/2 cup
2 cloves garlic chopped
5 Tablespoons flour
2 teaspoons chopped fresh thyme
1 cup milk
1 cup half and half
3/4 cup Parmigiano-Reggiano cheese grated
1/2 teaspoon kosher salt
1/2 teaspoon black pepper
1/8 teaspoon red pepper
10 ounces sweet potato peeled and sliced into 1/8" thick rounds, (1 medium)
8 ounces butternut squash peeled and sliced into 1/8" thick slices (about 1/2 medium)
1 pound russet potatoes peeled and sliced into 1/8" thick rounds
1/3 cup Gruyere cheese grated

Preheat over to 375 degrees F. Slice potato, sweet potato, and butternut squash into thin rounds, about 1/8″ slices. Bring a large pot of water to a boil and cook each vegetable separately for 4 minutes, or until almost tender. The vegetables will continue to cook in the oven.
Melt butter in a medium saucepan over medium heat. Add pancetta and cook one minute. Add shallots and garlic and cook another 2 minutes, stirring constantly.
Add flour and stir with whisk. Add thyme. Gradually add milk and 1/2 & 1/2 and stir constantly with a whisk over medium heat until slightly thickened, about 3 minutes. Stir in Parmigiano-Reggiano and blend until melted, about 3 minutes. Season to taste with salt and pepper.
Arrange a layer of potatoes in a buttered 11″ x 7″ casserole dish. Continue to layer casserole with sweet potato slices and butternut squash.
Spoon or pour cream sauce over potato mixture. Top with grated Gruyere cheese and bake at 375 degrees F. for 40 minutes.
Preheat broiler. Broil 3 minutes or until golden brown. Cover with aluminum foil until ready to serve.
Store in airtight container in the refrigerator for up to three days.