Preheat oven to 350 F.
Line a baking sheet with parchment paper and lightly spray with cooking spray.
Mix together the cake mix, pumpkin and pumpkin-pie spice in a large mixing bowl until there are no lumps.
Using a cookie scoop or tablespoon, drop balls of dough on the baking sheet and space them about 2-inches apart. Gently press down on each with the back of a spoon.
Bake for 12-15 minutes or until they turn golden brown.
Remove the cookies from the oven but leave them on the tray for 5 minutes, so they firm up.
Transfer the cookies to a cooling rack.
If frosting the cookies, make sure they are completely cooled before frosting them. With the powdered sugar, stir the sugar with water to make a glaze. Spoon over cooled cookies.
If using canned icing, transfer 1 cup of canned icing to a microwave-safe bowl and melt in the microwave starting at 30, stirring and increasing the time by 10-second intervals until it is a liquid. Spoon the melted icing over the cookies.
Cool the cookies completely before storing them in an airtight container with a lid.
Keep uneaten cookies in the refrigerator and take them out 10 minutes before serving, so they come to room temperature.
Enjoy!