In a small bowl, add gelatin and water; stir to combine and set aside to allow gelatin to bloom.
In a medium saucepan set over medium heat, add yolks, ½ cup cream, sugar, pumpkin puree, vanilla, spices, and salt. Cook, stirring constantly with a silicone spatula, until mixture thickens, about 5 minutes.
Whisk gelatin and water into pumpkin mixture and refrigerate for about 15 minutes. Once the mixture has come to room temperature, whisk the egg whites to medium peaks and fold into the pumpkin mixture.
Dump into the pie shell and let chill in the fridge, uncovered at least 4 hours but is best overnight.
Whip the whipping cream and maple syrup together right before serving.