In a medium saucepan, combine large marshmallows, pure pumpkin, cinnamon, pumpkin pie spice, and salt. Heat this mixture over low to medium heat, stirring frequently for about 8-10 minutes until the marshmallows are fully melted and the mixture is smooth and creamy, with an inviting orange hue.

Once your filling is silky smooth, carefully transfer it to a large mixing bowl. Allow it to cool at room temperature for approximately 30 minutes.

After the filling has cooled, gently fold in the thawed Cool Whip using a spatula. Be careful to combine the two mixtures thoroughly without deflating the whipped topping, which will take about 2-3 minutes.

Now, take your graham cracker crust and pour the pumpkin filling into it, smoothing out the top with your spatula.

Cover the pie with the crust lid or plastic wrap, then place it in the refrigerator. Allow it to chill for at least 8 hours or preferably overnight.

When ready to serve, remove the pie from the fridge and carefully uncover it. Slice into wedges and serve chilled, topped with whipped cream if desired.