In a mixing bowl, combine heavy cream, evaporated milk and salt.
With a stand mixer, beat until stiff peaks form gradually increasing speed to high, as mixture thickens. Stir sweetened condensed milk and chocolate syrup together in a bowl until it is mixed well. Slowly drizzle in sweetened condensed milk/chocolate syrup mixture starting mixer speed at low and gradually increasing it to high. Beat on high speed until stiff peaks form. Add vanilla extract.
Beat until it is well blended, maintaining stiff peaks.
Pour into a freezer-safe container with a cover. Freeze until firm and completely solid, about 8-10 hours.
In saucepan, whisk cocoa powder, sugar, water and salt. Bring to a rolling boil over medium heat. Boil for 1 minute, stirring constantly. Remove from heat. Stir in vanilla extract. Cool completely.