Mix graham crackers, butter, sugar and cinnamon together. Pat into pan and bake for 15 minutes at 350°. Cool about an hour. Mix cream cheese, powdered sugar and half of Cool Whip together. Put on top of cooled crust. Whip instant pudding and milk until thick. Put on top of cream cheese mixture and top with remaining Cool Whip. Sprinkle with nuts (optional). Refrigerate.