Let piecrust stand at room temperature as directed on package. Line a 9-inch pie plate with piecrust; fold under edge. Crimp as desired. Prick pastry all over with a fork. Sprinkle 2 teaspoons cinnamon-sugar mixture on the bottom crust. Line pastry with a double thickness of foil. Bake in a 450 degree F oven for 8 minutes. Remove foil. Bake for 5 to 6 minutes more or until golden. Cool on a wire rack. Set aside.
In a small saucepan, combine sugar (the amount of sugar depends upon the sweetness of the berries), cornstarch and salt. Stir in water. Bring to boiling; reduce heat. Stir in strawberry-flavored gelatin. Cook and stir over medium heat until thickened; remove from heat. Transfer gelatin mixture to a large bowl; cover and let cool to room temperature (about 1 hour).
Meanwhile, remove stems from strawberries. Cut any large strawberries in half lengthwise. Add berries to cooled gelatin mixture; stir gently to coat. Spoon strawberry mixture into cooled pastry shell. Cover; chill at least 4 hours or until firm. To serve, top with whipped cream. Sprinkle with additional spiced sugar, if you like.