Holiday Sides

Mixed Potato Gratin

MAKES 8 TO 10 SERVINGS

Have fun with the arrangement when shingling the colorful potato slices.

1½ pounds medium Yukon Gold potatoes, peeled
1½ pounds medium sweet potatoes, peeled and halved lengthwise
1¾ cups heavy whipping cream
⅓ cup minced garlic
¼ cup unsalted butter, softened
1 tablespoon chopped fresh sage
2 teaspoons kosher salt
2 teaspoons chopped fresh thyme
½ teaspoon ground black pepper
¼ teaspoon ground nutmeg
1 cup shredded Gruyère cheese, divided
½ cup shredded Parmesan cheese
Garnish: chopped fresh sage

1. Preheat oven to 400°. Butter an 11x8-inch baking dish; place on rimmed baking sheet. Fill a large bowl with cold water.

Using a very sharp knife or a mandolin, slice potatoes crosswise into ⅛-inch-thick slices. Add