Mix graham cracker crumbs, sugar, butter and ground cinnamon together in a bowl until fully incorporated.
Press mixture into an 8 or 9 inch pie pan. Bake at 375℉ for 6-7 minutes. Remove from oven and let cool for at least 30 minutes before adding pie filling (you can also cool in the fridge if needed).
Pie Filling
Combine cream cheese, 1 Tablespoon evaporated milk, and sugar with a whisk until smooth and fully combined.
Gently fold in Cool Whip.
Spread cream layer on the bottom of the cooled pie crust.
Pour remaining 1 cup evaporated milk into bowl.
Add dry pudding mixes (do not prepare pudding as directed on box - just use the dry pudding mix). Beat with wire whisk for 1 minute (mixture will be thick).
Stir in pumpkin puree and pumpkin pie spice with wire whisk until fully incorporated. Spread the mixture over the cream cheese layer.
Refrigerate for 4 hours or until set. If desired, top with whipped cream.
Notes
While I know it is convenient to just buy a container of pumpkin pie spice, there is just something about making your own blend for the delicious fall recipes.