1. Adjust oven rack to lower-middle position and heat oven to 425°F. Process nuts, flour, brown sugar, 2 tablespoons granulated sugar, cinnamon, nutmeg, and 1/8 teaspoon salt in food processor until nuts are finely chopped, about nine 1-second pulses. Drizzle butter over flour mixture and pulse until mixture resembles crumbly wet sand, about five 1-second pulses, pausing halfway through to scrape down sides and bottom of workbowl. Add oats to food processor and process until evenly incorporated, about three 1-second pulses. Set aside while preparing fruit.

2. Whisk remaining 2 tablespoons granulated sugar, cornstarch, lemon juice, and pinch of salt together in large bowl. Peel pears, then halve and core each. Cut each half into 4 wedges and then cut in half crosswise (pieces should be about 1 1/2 inches). Gently toss pears with sugar mixture and transfer to 8-inch-square baking dish.

3. Sprinkle topping evenly over fruit, breaking up any large chunks. Bake until fruit is bubbling around edges and topping is deep golden brown, 27 to 32 minutes. Cool on wire rack until warm, at least 15 minutes, and serve.

Serves 6