Preheat oven to 180°C. Grease a baking dish (about 20 x 15cm). Bring a full kettle to the boil.
In a large bowl, whisk together milk, egg and melted butter. Add chocolate pudding mix. Whisk gently until smooth and combined. Pour into prepared dish and smooth into an even layer with a spoon.
Sprinkle chocolate sauce mix evenly over pudding. Slowly pour boiling water onto the back of a large metal spoon over the pudding, to cover evenly. Place baking dish on a baking tray (to prevent any spills while baking). Bake for 25-30 minutes, or until pudding bounces back when pressed gently in centre. Serve immediately.
Dust with icing sugar and serve with cream.