In small microwavable bowl, microwave chocolate chips, 1 tablespoon butter and the whipping cream uncovered on High 1 to 2 minutes, stirring every 30 seconds, until chips are completely melted. Spread over pineapple layer. Refrigerate about 1 hour or until set. For 36 bars, cut into 6 rows by 6 rows. Store covered in refrigerator.