To prepare pastry: Preheat oven to 375°F. In a medium bowl, stir together 1¼ cups flour and salt. Combine ¼ cup milk and oil; add all at once to flour mixture. Stir with a fork until dough forms. If necessary, add 1 to 2 teaspoons additional milk. Shape the dough into a ball.
Cut wax paper into two 12-inch squares. Place dough between paper. Roll into a circle to edges of paper. (Dampen work surface with a little water to prevent paper from slipping.) Peel off top paper and fit dough, paper side up, into a 9-inch pie plate. Remove top paper. Trim dough to ½ inch beyond edge of pie plate. Fold under extra pastry. Crimp the edge as desired. Do not prick pastry.
To prepare filling: In a medium bowl, combine pumpkin, syrup, sugar, flour and pumpkin pie spice; add egg. Stir until just combined. Gradually stir in evaporated milk and vanilla; mix well.
Pour filling into pastry shell. To prevent overbrowning, cover edge of pie with foil. Bake for 25 minutes. Remove the foil. Bake 25 to 30 minutes more or until center is set. Cool on a wire rack. Cover and refrigerate within 2 hours. If desired, top with dessert topping and sprinkle with ground cinnamon.
Tips: Sugar Substitute: We do not recommend using sugar substitute in place of the sugar in this recipe.