PreparationFor topping: Mix flour, oats, brown sugar, cinnamon, and salt in medium bowl. Add butter and rub in with fingertips until mixture comes together in moist clumps. Stir in walnuts. Do ahead: Can be made 1 day ahead. Cover and chill. For filling: Position rack in center of oven and preheat to 350°F. Mix sugar, cornstarch, cinnamon, and salt in large bowl. Add apricots and toss to coat. Transfer apricot mixture to 11x7x2-inch glass baking dish. Sprinkle topping over. Bake crisp until filling is bubbling around edges and topping is crisp and golden, about 1 hour. Cool at least 20 minutes. Serve warm with ice cream.
PreparationFor topping: Mix flour, oats, brown sugar, cinnamon, and salt in medium bowl. Add butter and rub in with fingertips until mixture comes together in moist clumps. Stir in walnuts. Do ahead: Can be made 1 day ahead. Cover and chill. For filling: Position rack in center of oven and preheat to 350°F. Mix sugar, cornstarch, cinnamon, and salt in large bowl. Add apricots and toss to coat. Transfer apricot mixture to 11x7x2-inch glass baking dish. Sprinkle topping over. Bake crisp until filling is bubbling around edges and topping is crisp and golden, about 1 hour. Cool at least 20 minutes. Serve warm with ice cream.