Line an unpricked pastry shell with a double thickness of heavy-duty aluminum foil.
Bake the pastry shell in the preheated oven for 8 minutes.
Remove foil; bake 5 minutes longer. Cool on a wire rack.
Place the sugar, cornstarch, and water in a saucepan. Cook over medium heat until the sugar and cornstarch dissolve and the mixture thickens, about 10 minutes.
Remove from heat and whisk in the raspberry flavored gelatin mix. Refrigerate the filling until slightly cooled, about 15 minutes.
Arrange the raspberries evenly in the bottom of the prepared pie crust.
Pour the raspberry gelatin mixture over the berries. Chill the pie in the refrigerator until set, 4 to 6 hours.
