Spread around 1 cup Cool Whip on the flat side of half of the 24 vanilla wafer cookies.
Place remaining vanilla wafer cookies flat-side down onto the Cool Whip-covered ones to make "cookie sandwiches."
Add around 1/2 cup nonpareil sprinkles to a shallow bowl, then roll the edges of each cookie sandwich in the sprinkles to coat the edges of the Cool Whip.
Place cookie sandwiches on parchment paper-lined baking sheet and put in freezer until Cool Whip is frozen solid. When frozen, transfer to a sealed zip-top freezer bag or freezer-safe storage container.