To make the chocolate syrup, combine sugar, water, cocoa powder, vanilla and salt in a large saucepan. Mix well
Cook over a medium heat until the mixture is boiling. Stir occasionally.
Reduce heat and simmer for 5 minutes taking care it does not boil over. Stir frequently.
Allow to cool and bottle in a recycled squeeze ketchup bottle.
To make a hot chocolate drink, heat milk to the required temperature. Squirt chocolate syrup around the inside of clear drinking glasses and immediately pour in warm milk.