Serves SERVES 6
- 2 pounds russet potatoes, peeled and sliced ¼ inch stick
- 4 tablespoons extra-virgin olive oil
- 2 teaspoons kosher salt
- 2 medium onions, sliced ¼ inch thick
- 6 large fresh sage leaves, coarsely chopped
- 1 cup Chicken Stock, Vegetable Stock, or water (see Headnote above)
- 1 ½ cups grated Italian Fontina
- ½ cup freshly grated Grana Padano
Preheat the oven to 450 degrees. In a large bowl, toss the potatoes with 2 tablespoons of the oil and 1 teaspoon of the salt. In another large bowl, toss the onions with the remaining 2 tablespoons oil and the remaining teaspoon salt.
Spread half of the potatoes in a layer in a 9-by-13-inch baking dish, and scatter half of the sage over them. Top with all of the onions and the rest of the sage. Top with the remaining potatoes, and pour the stock over all. Cover with foil, and bake until potatoes and onions are tender, about 20 to 25 minutes.
In a medium bowl, toss the cheeses together. Uncover the pan, sprinkle the cheese on top of the potatoes, and bake until the cheese is browned and bubby, about 15 minutes more. Serve hot.