In a mixing bowl, combine crushed graham crackers and melted butter until the crumbs are well-coated. Press this mixture firmly into the bottom of a 9x13-inch baking dish to create an even crust. Chill the crust in the refrigerator for 15 minutes, allowing it to set and become crisp.

In a separate bowl, whisk together the instant vanilla pudding mix and milk for about 2 minutes until the mixture thickens and becomes smooth. Ensure the pudding is lump-free and maintains a creamy consistency.

Gently fold in the plain canned pumpkin puree and pumpkin pie spice into the thickened pudding mixture.

Take the chilled crust from the fridge and carefully spread the pumpkin cheesecake filling over it. Use a spatula to smooth the top evenly.

Once the pumpkin cheesecake layer is smooth, spread the whipped topping over the pumpkin layer. Dust the top with additional pumpkin pie spice for an aromatic finish.

Cover the whole dish with plastic wrap and chill in the refrigerator for at least 4 hours, or ideally overnight.