Combine your graham cracker crumbs with melted butter in a bowl until the mixture looks like wet sand. Press this firmly into the bottom of your baking dish. Bake at 350°F for about 10 minutes, then let it cool completely before adding anything on top.
Beat the softened cream cheese, powdered sugar, and vanilla together until completely smooth. Fold in about a third of the whipped topping to lighten the mixture. Spread this evenly over your cooled crust using a spatula.
Whisk the cold milk with both boxes of instant pudding mix until it starts to thicken. Stir in the pumpkin puree and pumpkin pie spice until everything is fully combined and smooth. Pour this layer over the cream cheese layer and spread it out evenly.
Spread the remaining whipped topping over the pumpkin pudding layer, covering it completely from edge to edge. This final layer is what gives the dessert its light, cloud-like finish on top.
Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, though overnight works even better. Right before serving, sprinkle chopped pecans or a light dusting of extra pumpkin spice over the top.