Mix crumbs and butter, press firmly onto the bottom of a 9” springform pan. Refrigerate 10 minutes. Beat cream cheese, peanut butter and sugar with an electric mixer until well blended. Stir 1/2 of the chocolate into the cheese mixture. Gently stir in 1 cup of Cool Whip. Spoon over crust and refrigerate for 3 hours.
Microwave remaining 1/2 cup Cool Whip and chocolate in a small microwaveable bowl on high for 1 minute; cool slightly and pour over cake. Refrigerate until ready to serve.