Combine 1/4 cup flour and ice water, stirring with a wire whisk until well-blended; set aside. Combine remaining 3/4 cup flour, sugar, and 1/4 teaspoon salt in a bowl; cut in shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Add ice water mixture; mix with a fork until dry ingredients are moistened. Gently press mixture into a 4-inch circle on heavy-duty plastic wrap, and cover with additional plastic wrap. Roll the dough, still covered, into an 11-inch circle, and chill for 10 minutes or until the plastic wrap can be easily removed.
Remove 1 sheet of plastic wrap; fit dough into a 9-inch pie plate coated with cooking spray, and remove top sheet of plastic wrap. Fold edges under, and flute; prick bottom and sides of dough with a fork. Bake at 400° for 15 minutes; let cool on a wire rack.
Combine pumpkin and the next 13ingredients (pumpkin through egg) in a bowl, and stir well with a wire whisk. Pour into prepared crust; bake at 400° for 40 minutes.
Combine the pecans, 1/4 cup brown sugar, corn syrup, and 1/2 teaspoon of vanilla, and stir well. Sprinkle pecan mixture over pie, and bake an additional 15 minutes or until filling is set (shield the edges of piecrust with aluminum foil, if necessary). Let cool completely on a wire rack.