Step 1Heat the oven to 350 degrees. Spread the nuts on a baking sheet and toast them until they're fragrant and lightly browned, 8 to 10 minutes. Set them aside.
Step 2Peel and core the apples and pears and cut them into 1-inch chunks. Spread the fruit evenly over the bottom of a shallow 2-quart baking dish. If desired, sprinkle the fruit with the brandy or rum.
Step 3Combine the flour, granulated and brown sugars, lemon zest, salt, cinnamon and nutmeg in a mixing bowl. Using a pastry blender, two knives or your fingers, cut the butter into the dry ingredients until the mixture resembles coarse bread crumbs. Mix in the nuts.
Step 4Spread the topping evenly over the fruit. Bake the crisp until the fruit is tender and the crust is lightly browned, 40 to 45 minutes. Serve warm, if desired, with vanilla ice cream.