Lightly spoon flour into dry measuring cups; level with a knife. Combine 1 cup flour and 1/4 teaspoon salt in a bowl; cut in 1/4 cup shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Sprinkle surface with ice water, 1 tablespoon at a time; toss with a fork until moist and crumbly (do not form a ball).
Press mixture gently into a 4-inch circle on heavy-duty plastic wrap; cover with additional plastic wrap. Roll dough, still covered, to a 12-inch circle. Freeze 10 minutes or until plastic wrap can be easily removed.
Remove 1 sheet of plastic wrap; fit dough into a 9-inch pie plate coated with cooking spray. Remove top sheet of plastic wrap. Fold edges under; flute.
Preheat oven to 350°.
Combine 1 cup flour, 1/4 teaspoon salt, and brown sugar in a bowl; cut in 3 tablespoons shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Combine boiling water and baking soda; stir in molasses. Pour molasses mixture into prepared crust; sprinkle flour mixture over molasses mixture. Place pie on a baking sheet; bake at 350° for 40 minutes or until set. Cool on a wire rack.