Preheat oven to 350 degrees F. Spray a 9x13 pan with cooking spray. Set aside.
Make the crust:
Pulse graham crackers in food processor to make crumbs.
In a medium-sized mixing bowl combine graham cracker crumbs, sugar and melted butter. Spread graham cracker mixture on the bottom of the baking pan and flatten with the bottom of glass to form a crust. Bake for 5-7 minutes. Remove from oven and let cool.
While the crust is cooking make the cheesecake layer.
In a stand mixer mix cream cheese and powdered sugar until combined.
Gently mix in whipped topping.
Carefully spread the cheesecake mixture on top of the crust.
Set in refrigerator while you make the pumpkin layer.
Make the pumpkin layer.
In medium-sized mixing bowl combine half and half and vanilla pudding. Mix until it thickens.
Add pumpkin and pumpkin pie spice and mix until combined.
Gently fold in 1/2 cup cool whip.
Spread on top of the child cheesecake layer.
Finally, add 8 oz. of Cool Whip. Sprinkle with chopped nuts.
Refrigerate 1-2 hours.