For the Pastry: Preheat the oven to 425 degrees F. Lay the frozen pastry shells on a cookie sheet with the “top” side up. Bake in a preheated oven for about 20 minutes or until the pastries are golden brown and puffed. Sometimes as the pastries rise they may tip over or lean to one side. If this happens, once they're done baking, just bend them back into an upright position. Remove the top circles from the pastry shells with your fingers or with a fork. Set the pastries aside on a rack to cool.
For the Pudding: In a medium size bowl, add the pudding mix and cold milk according to the package instructions. Beat with a whisk for 2 minutes (or according to package instructions). Chill for 15 minutes in the refrigerator.
For the Pumpkin Pudding Puffs: Spoon the pudding into the shells. Fill each shell to the top with pudding.
For the Topping and Garnish: Top with Cool Whip topping or whipped cream. Lightly sprinkle cinnamon on top of the Cool Whip to garnish and serve. The puff pastry shell tops can be used for garnish or made into small pudding and Cool Whip sandwich puffs. Store leftovers in the refrigerator.