Sweet caramelized shallots and crispy sage leaves bump up the flavor profile of this simple potato gratin. These two easy additions take the classic side dish from average to amazing.
For the gratin:1.
Preheat the oven to 375°F.2.
Peel the potatoes and thinly slice them 1/8-inch thick on a mandoline. Place in a large bowl, cover with cold water, and let soak for at least 10 minutes, or up to 4 hours. Drain well and pat dry.3.
Arrange a single layer of the potato slices over the bottom of a 10-inch square casserole or 3½-quart baking dish with 2-inch-high sides. Drizzle with 3 tablespoons of the cream and season with salt and pepper. Repeat with the remaining potatoes, cream, salt and pepper to form eleven layers. Press down on the layers to totally submerge the potatoes in the cream mixture.4.
Cover with foil and bake for 30 minutes. Uncover and bake until the cream has been absorbed, the potatoes are cooked through, and the top is browned, 30-45 minutes more.
For the caramelized shallots:
While the gratin bakes, melt the butter in a large sauté pan over medium heat. Add the shallots and sugar and slowly cook, stirring occasionally, until golden brown and caramelized, about 40 minutes; season with salt and pepper. Set aside.
For the fried sage leaves:
Line a plate with paper towels and set it nearby. Heat the oil in a small saucepan over medium heat until it begins to shimmer.
Working in batches, add the sage leaves and fry for a few seconds, until crisp. Using a slotted spoon, transfer the sage to the paper towel-lined plate and season with salt. (Let the sage-infused oil cool and save it to use for sautéing fish, chicken or pork chops. It will keep in the refrigerator, tightly covered, for up to 1 month.)
Top the baked gratin with the caramelized shallots and fried sage leaves. Let rest for 10 minutes before slicing.