In a medium saucepan, combine large marshmallows, pure pumpkin, cinnamon, pumpkin pie spice, and a pinch of salt over low to medium-low heat. Stir continuously for about 5-7 minutes until the marshmallows are fully melted and the mixture appears smooth and glossy.

Transfer the warm marshmallow-pumpkin mixture into a mixing bowl and allow it to cool to room temperature for about 30 minutes.

Once the mixture has cooled completely, gently fold in the thawed Cool Whip using a spatula or large spoon. Mix until fully incorporated and fluffy.

Carefully pour the fluffy filling into the prepared graham cracker crust, smoothing the top for a beautiful finish.

Cover the pie and refrigerate for at least 8 hours, preferably overnight.

Once set, slice the pie and serve chilled, optionally topped with whipped cream.