Combine water, sugar and corn syrup in a medium saucepan and bring to a low boil over medium-high heat. Once boiling, reduce heat to low and whisk in cocoa powder and salt until well combined.
Continue to cook for 3-4 minutes or until slightly thickened. Add in vanilla and cool before storing n a squeeze bottle (you can even store it in an old hershey’s bottle and no one will be the wiser).