Place raspberry chips and milk in large microwave-safe bowl. Microwave at
HIGH (100%) 1 minute or until chips are melted and mixture is smooth when stirred.
Add marshmallows; microwave at HIGH 1 minute; stir. If necessary, microwave
at HIGH an additional 30 seconds at a time, stirring after each heating, just
until marshmallows are melted when stirred. Spread 1/2 cup chip mixture over
bottom of crust.
Cool remaining mixture to room temperature; fold in whipped topping. Spoon
into crust. Cover; refrigerate 4 to 6 hours or until firm.