1. In small, heavy saucepan, combine chocolate, butter and corn syrup. Place over medium-low heat; cook, stirring until chocolate and butter are melted, 3 to 4 minutes. Add sugar and cream; cook, stirring 2 minutes or until sugar is dissolved. Increase heat to medium. Bring to a gentle boil; boil 8 minutes, without stirring.
2. Remove pan from heat. Stir in vanilla and salt. Spoon hot sauce over ice cream.To store sauce:
3. Let cool completely before covering. Store, tightly covered, in refrigerator up to 1 week. To warm, place over warm water and stir. Or microwave on high power 1 minute, stirring halfway through. If necessary, continue heating on high, checking after 10-second intervals.