Step 1

In a medium, heavy saucepan over medium heat, combine cream, corn syrup, brown sugar, cocoa, salt, and half of the chocolate. Bring the mixture to a boil, stirring until the chocolate pieces are completely melted.

Step 2

Reduce heat and cook at a low boil, stirring occasionally, for about five minutes. Remove the pan from the heat and add in butter, vanilla, and remaining chocolate, stirring until smooth.

Step 3

Allow the sauce to cool down before serving.