In a glass or small bowl, combine two tablespoons of milk with the chocolate chips, cocoa powder, sugar, and salt, and whisk together. Microwave for 30 seconds, and whisk again so that the mixture is like ganache. Add the vanilla and whisk again. The chocolate mixture should be smooth. Add the cup of milk and whisk again, and then microwave for 90 seconds or to desired temperature. Whisk once more and then pour into a glass or mug for serving. Top with marshmallows or whipped cream, and enjoy!