Stir the gelatin and cold water together in a small bowl and set aside for at least 5 minutes.
Making sure they are about room temperature, separate the eggs. Crack the whites into a medium mixing bowl and set aside. In another bowl, beat the yolks with the pumpkin puree, 1/2 cup sugar, milk, salt and spices (cinnamon, nutmeg and ginger).
Cook the mixture in a medium sauce pot over medium-low heat until it begins to simmer and thicken, stirring occasionally. Cook for 8-10 minutes.
Add gelatin / water mixture to the pumpkin and stir until it dissolves completely. Remove from heat and let cool completely- you don't want it even a little warm for the next step.
Once the pumpkin mixture has cooled to at least room temperature, beat the egg whites on high speed. Add the last 6 tbsp sugar, 1 tbsp at a time, continuing to beat until all sugar is incorporated and stiff peaks begin to form.
In as few motions as possible, fold egg whites into the pumpkin mixture until they are fully incorporated. Pour into your prepared crust. Chill until firm, at least overnight. Serve with whipped cream.