2 tablespoons unsalted butter, plus more for preparing baking dish
4 cups thinly sliced onions (about 1 pound)
1 1/4 pounds butternut squash, peeled, seeded and sliced 1/4 inch thick
1 1/4 pounds Yukon Gold potatoes, peeled and sliced 1/4 inch thick
1 cup half-and-half
1 teaspoon salt
1/2 teaspoon freshly ground black pepper
2 cups fresh breadcrumbs made from sourdough bread
8 ounces shredded Gruyere cheese (about 2 cups, packed)
1 1/2 tablespoons chopped fresh sage
Butter a 9-by-13-inch baking dish. In a large, heavy skillet, melt the 2 tablespoons butter over medium-high heat. Add the onions and saute until onions are deeply caramelized, about 20 to 30 minutes.
Meanwhile, preheat oven to 350 F.
Arrange alternating layers of the squash and potatoes in prepared baking dish. Layer cooked onions on top. Mix the half-and-half, salt and pepper and pour over onions. Cover tightly with foil and bake in preheated oven for 90 minutes.
Increase oven temperature to 400 F. In a medium bowl, mix the breadcrumbs, cheese and sage. Sprinkle over gratin. Bake uncovered until top is golden-brown and crisp, about 30 minutes. Makes 8 servings.
— Recipe from "The Oregonian Cookbook: Best recipes From FOODday," edited by Katherine Miller.