1. Place the marshmallows, pumpkin purée, cinnamon, pumpkin-pie spice, and salt in a small saucepan over low to medium-low heat. Stir constantly as the marshmallows melt and everything becomes a smooth, combined mixture. Keep the heat gentle so nothing scorches.
2. Pour the hot pumpkin-marshmallow mixture into a bowl and let it cool to room temperature. This usually takes around 30 minutes; it’s important so the whipped topping doesn’t melt when mixed in.
3. Once the pumpkin mixture has cooled, fold in the thawed Cool Whip until the filling is uniform and noticeably lighter in color and texture.
4. Spoon the filling into the prepared graham cracker crust and spread it evenly.
5. Cover the pie (use the crust’s lid or wrap tightly) and refrigerate for at least 8 hours, or overnight for best texture. Chilling allows the filling to firm up and become sliceable.
6. When ready to serve, top slices with additional whipped cream, if desired. (Tip: don’t add the whipped garnish while storing — it will weep and soften.)

Homemade Whipped Cream Option

1. If you prefer fresh whipped cream instead of Cool Whip, whip together 1½ cups cold heavy cream with ⅓ cup powdered sugar on medium-high speed until stiff peaks form (about 4–5 minutes). Use this in place of the Cool Whip in the recipe.