In a medium saucepan, combine the milk with the sugar, espresso powder and salt. Cook over moderate heat until the milk is steaming and a few bubbles appear around the edge of the pan, about 5 minutes. Remove from the heat and add the chopped chocolates. Let stand for 1 minute, then whisk until smooth. Whisk in the cream and keep warm.
In a medium bowl, beat the cream with the sugar until firmly whipped.
Ladle the hot chocolate into cups or mugs. Top with dollops of whipped cream and serve.
