1. Combine water, corn syrup, and sugar in a nonreactive pan and bring to a boil, stirring often, until all the sugar crystals have melted. Boil 1 minute without stirring.
2. Remove from heat and add the salt and the chocolate. Allow to stand 2 minutes until chocolate has melted, then whisk smooth.
3. Sift the cocoa into a mixing bowl and stir in enough of the liquid mixture to make a paste, then stir the cocoa paste smoothly back into the syrup.
4. Whisk in the remaining ingredients.
5. Store the sauce in a tightly covered jar in the refrigerator. Reheat over simmering water before serving.
This recipe is from the book Chocolate, From Simple Cookies to Extravagant Showstoppers
by Nick Malgieri.