To make the topping, in a medium bowl, add flour, oats, brown sugar, walnuts, cinnamon, and salt. Drizzle butter over mixture and toss to combine. Cover an refrigerate while preparing the filling.
Adjust an oven rack to the lower-middle position and preheat to 350 degrees. Coat a 9-inch by 13-inch baking dish with nonstick spray or rub with butter.
In a large bowl, whisk together sugar, cinnamon, nutmeg, and salt. Add pears and toss well to coat. Pour intro prepared baking dish and sprinkle with topping.
Bake until the fruit juices are bubbling and the topping is crisp and golden brown, about 50 to 60 minutes. Remove from oven and cool 15 minutes. Serve with vanilla ice cream if desired.
Rolled oats: Flat and flaky, these are otherwise known as "old-fashioned" oats. Quick-cooking oats can work in a pinch, but do not substitute steel-cut oats.
Walnuts: I think the walnuts add a wonderful flavor and crunch to the topping, but it's okay to leave them out if you prefer. I've also done testing with raw pecans and raw cashews, and they were both excellent.
Pears: Look for ripe, juicy pears such as Bartlett, Bosc, or Asian pears. There is no need to peel them before coring and slicing.
Yield: This recipe makes about 6 cups of Pear Crisp, enough for 8 servings, 3/4 cup each (plus ice cream).
Storage: Cover the Pear Crisp with foil or plastic wrap and store at room temperature for 1 to 2 days or store covered in the refrigerator for up to 4 days.