Prepare Crust: Combine flour and salt; cut shortening into flour mixture with a pastry blender or fork until mixture resembles small peas. Sprinkle ice water, 1 Tbsp at a time, over mixture in bowl; stir with a fork until dry ingredients are moistened. Shape dough into a ball; cover and chill 1 hour.
Preheat oven to 450°. Roll dough to ⅛-inch thickness on a lightly floured surface. Fit into a 9-inch pie plate; trim off excess pastry along edges. Fold edges under, and crimp. Line pastry with aluminum foil, and fill with pie weights or dried beans.
Bake at 450° for 8 minutes. Remove weights and foil; bake 1 minute. Remove crust from oven to a wire rack. Reduce oven temperature to 350°.
Prepare Topping: Pulse pecans and brown sugar in a blender or food processor 4 times or until finely chopped.
Prepare Filling: Whisk together pumpkin and next 11 ingredients in a large bowl. Pour into prepared crust.
Remove from oven, and top with pecan mixture. Bake 15 more minutes or until set. Cool completely on a wire rack. (about 3 hours!)
