Apple and Sweet Potato Tart

Heat oven to 425 degrees F. Fit the pie crust into the bottom and about 1 1/2 inch up the sides of a 9-inch springform pan. Arrange half of the sweet potato in the bottom of the pan, placing slices in concentric circles. Top with half the onion, then half the apple. Sprinkle with half the sage, drizzle with 1 teaspoon oil, and sprinkle with 1/4 teaspoon each salt and pepper. Top with half the Yukon gold potatoes and half the cheese. Top with the remaining onion, apple, and Yukon gold potatoes. Sprinkle with the remaining sage, drizzle with the remaining oil, and season with 1/4 teaspoon each salt and pepper. Arrange the remaining sweet potato on top and sprinkle with the remaining 1/2 cup cheese. Cover with foil, place the pan on a baking sheet, and bake for 30 minutes. Remove foil and bake until the vegetables are tender and the top is beginning to brown, 10 to 12 minutes more. Let cool for 5 minutes in the pan, then transfer to a serving platter. Serve with mixed green salad, if desired.