Heat cream, salt and corn syrup in microwave safe measuring cup on high until simmering, about 1 minute.
Place chocolate in workbowl of food processor fitted with steel blade.
With machine running, gradually add hot cream mixture through feed tube; process 1 minute.
Add powdered sugar to workbowl and process to combine, about 30 seconds.
With machine running, add butter through fed tube one piece at a time process until incorporated and smooth.
Transfer frosting to medium bowl and cool at room temperature stirring frequently until thick and spreadable, about 1 hour.