In a saucepan, over low or medium-low heat, combine the marshmallows, pumpkin, cinnamon, pumpkin pie spice, and salt.
Stirring very frequently, let it melt and mix together until it's smooth and combined.
Transfer the hot mixture to a mixing bowl and let it cool to room temperature- about 30 minutes.
Once cooled, add the thawed Cool Whip and stir together until thoroughly combined and much lighter in color.
Pour the mixture inside the graham cracker crust and spread it out evenly.
Cover the pie and put it in the fridge for at least 8 hours to thicken up and come together. Or you can refrigerate it overnight as well.
Slice and serve with additional Cool Whip or freshly whipped cream.