In a saucepan over low or medium-low heat, combine the large marshmallows, canned pumpkin puree, ground cinnamon, pumpkin pie spice blend, and salt. Stir very frequently to prevent the mixture from sticking, letting everything melt together until smooth and fully combined. I sometimes add the salt last to taste, which really helps balance the sweetness.

Transfer the hot, smooth pumpkin-marshmallow mixture from Step 1 into a large mixing bowl. Allow it to cool to room temperature before proceeding, about 30 minutes or longer if needed. This ensures the whipped topping doesn't melt when added.

Once the pumpkin mixture is completely cool, add the thawed Cool Whip. Stir gently until everything is evenly combined and the filling has a much lighter, fluffy texture. Be careful not to overmix, as this will help keep the pie light and airy.

Spoon the pumpkin pie filling from Step 3 into the prepared graham cracker crust. Spread it out evenly, smoothing the top with a spatula for a nice presentation.

Cover the pie with the enclosed lid from the crust and refrigerate for at least 8 hours, or overnight for best results. This allows the filling to thicken and the flavors to come together. I always let it chill overnight—it slices perfectly afterward.

When ready to serve, slice the chilled pie and top each piece with additional whipped cream. You can use spray can whipped cream, more Cool Whip, or even homemade whipped cream—it's up to you. Dollop just before serving to keep it fresh.