Ingredients

3 tablespoons unsalted butter, melted

3 tablespoons extra-virgin olive oil

4 pounds russet potatoes, peeled

4 shallots, thickly sliced lengthwise

course salt

1/2 to 1 teaspoon red-pepper flakes or Italian red pepper mix

Preparation

  1. Preheat oven to 375 degrees. In a small bowl, combine butter and oil. Brush bottom of a round 9-inch baking dish with some butter mixture. With a sharp knife or mandoline, slice potatoes very thinly crosswise. Soak in water if doing a large batch to avoid discoloration.

  2. Arrange potato slices vertically in dish. Wedge shallots throughout. Sprinkle with salt and red-pepper mix; brush with remaining butter mixture. Bake 1 1/4 hours. Add thyme and bake until potatoes are cooked through with a crisp top, about 35 minutes more.