Combine sugar, gelatin, cinnamon, all-spice, nutmeg, ginger, and salt in a saucepan.
Stir in milk, and cook over medium heat until the gelatin is dissolved.
Place the egg yolks in a medium bowl and slowly add half the milk mixture to the eggs, whisking constantly to temper the yolks.
Add the egg mixture to the saucepan.
Stir in the pumpkin puree, and bring to a gentle boil.
Cook for 3 minutes, stirring.
Pour mixture into a large bowl, cover, and refrigerate for 30 minutes, stirring every 10 minutes.
In the meantime, combine 35% cream with 2 tablespoons of white sugar.
Beat on high until soft peaks form.
Fold whipped cream into chilled pumpkin mixture until combined.
Pour into graham crust.
Cover and chill at least 4 hours to overnight.
When ready to serve, cut into 8 wedges and top with additional whipped cream or ice cream.
Store leftover pie in the fridge.