Add sugar and water to a heavy pot and cover with a lid - heat on very low heat until the sugar is dissolved. You can stir it occasionally to speed up the process.

Once dissolved, add butter and increase the heat to bring the mixture to a low boil, stirring occasionally for about 6-9 minutes.

Turn off heat and add the cocoa, salt and vanilla. Whisk to combine.

Pour into your storage container. Optional, blend with an immersion blender to get a silky smooth consistency.

Store in the refrigerator - this will last for months! The syrup will thicken over the course of the day.