Chop the chocolate very finely and place it into a bowl. Heat the cream in a saucepan over medium heat. Bring just to boil and pour it over the chopped chocolate, add the espresso and whisk until smooth. Pour into 4 cappuccino cups. Place it in the fridge and let it cool down. In the meantime prepare your meringue by beating the sugar and egg whites together to form soft peaks. Take the cups from the fridge and sprinkle a tablespoon of crushed biscuit over the top of each one. Fill every cup with meringue to the top (like you would do with your milk in a cappuccino) and burn the meringue with a blow torch. Sprinkle the surface with cocoa powder and serve.