In a medium bowl, combine the peanut butter and chocolate syrup. Whisk in 1 cup of cool whip until combined well. Gently fold in the remaining cool whip. Place 40 Nilla wafers (flat side up) onto a cookie sheet and place 1 tablespoon of the cool whip mixture on top of each wafer. Place into the freezer for 10 minutes. Remove from the freezer and add the remaining 40 Nilla wafers on top (flat side down). Cover with plastic wrap and return to freezer for 2-3 hours. Once frozen, place in an airtight container and store in the freezer.