Step 1

Mix the sugar, cocoa, cornstarch and salt in a heavy medium saucepan. Add half of the milk and whisk until the mixture is smooth. Whisk in the remaining milk. Continue whisking over medium heat until the pudding thickens and comes to boil, about 8 minutes. Continue to boil 1 minute longer, whisking constantly.

Step 2

Remove the pudding from the heat. Add the chopped chocolate and vanilla; whisk until the chocolate melts and the pudding is smooth. Divide between 4 dessert dishes. Cover the puddings by placing a small piece of saran wrap inside the dessert dishes and directly over the pudding (this prevents a film from developing at the top). Cool the puddings in the refrigerator until cold and set, 2-3 hours, and then top with whipped cream and toppings and serve.