Stir gelatin in cool water, set aside.
Mix sugar, salt, egg yolks, milk, cinnamon, and pumpkin in a kettle.
Cook, stirring constantly until thickened.
Remove from heat and add gelatin, soaked in water.
When cooled, beat the egg whites and add to pumpkin mixture.
Pour this on top of cooled crust.
Let stand in refrigerator a few hours and top with whipped topping and if desired, sprinkle with cinnamon.