Beat milk and pudding mix in a large-deep bowl, for 2 minutes.
Blend in the pumpkin and spices.
Stir in the 1 cup of Cool Whip, and refrigerate for 1 hour.
Layer the pumpkin mousse and additional Cool Whip into a trifle bowl, or parfait glasses. (Or use other individual glasses of your choice.)
Top each dessert with a light sprinkle of the ground cinnamon.
Serve immediately, or place the dessert in the refrigerator until ready to serve.
Note: Depending on the size of dessert glasses you are using, and how much of the pumpkin mousse and whipped topping you layer into them, that pretty much will determine the servings you will get.
Optional variation: Omit layering the additional Cool Whip and the pumpkin mousse. Just add the pumpkin mousse into smaller individual serving dishes, and top each with a dollop of Cool Whip and a light sprinkle of the ground cinnamon. This will yield more servings.