Combine Milk, Cocoa, Sugar & Salt in a medium saucepan.
Heat Until Steaming. Whisk this mixture over medium heat to combine. Heat until mixture is steaming, but not boiling. (At first, it will seem like the cocoa isn't going to blend in, but as it heats and the cocoa "blooms," it will blend it smoothly.)
Stir In Chocolate & Vanilla, stirring over low heat until the chocolate is fully dissolved. (Again, at first, it will seem like the chocolate gets grainy. Don't panic! Just keep stirring.
Serve with your favorite toppings--whipped cream, marshmallows, and more!