In 1-quart resealable freezer plastic bag, place chocolate chips and oil; seal bag. Microwave on High 35 to 60 seconds, squeezing chips in bag every 15 seconds, until chips are melted and mixture is smooth. Cut small tip from bottom corner of bag. Drizzle chocolate over truffles. Refrigerate about 15 minutes or until chocolate is set. Store covered in refrigerator.