Place a medium saucepan on the stove and set it on medium-high heat.
Add ¼ water, cocoa powder, cane sugar, corn syrup, and salt to the saucepan.
Stir the mixture for around 10 minutes until they boil.
Once the ingredients form a thick consistency, add the remaining water.
Continue stirring until you achieve the desired consistency.
After this, remove the saucepan from the stove.
Give the mocha sauce a few minutes to cool.
You can now add 1 tsp of vanilla extract and then stir.