In medium microwavable bowl, microwave caramels and cream uncovered on High 2 minutes, stirring every 30 seconds, until melted and smooth. Very slowly pour caramel mixture over fudge layer, and gently spread to cover. Sprinkle with salt and 1 1/2 cups caramel popcorn; press gently so it sticks. Refrigerate until firm, about 2 hours. Cut into 1-inch squares (8 rows by 8 rows). Store covered in refrigerator.