Preheat the oven to 180C/350F/Gas 4. Grease a 20cm x 12cm/8in x 5in ovenproof dish with butter.
In a large bowl, whisk together the milk, cream, eggs, egg yolks, sugar and vanilla extract until smooth.
Place the bread and chocolate pieces into the base of the dish and pour over the custard mixture.
Transfer to the oven and bake for 15 minutes, or until the custard has set and the pudding is golden-brown on top.
Serve warm, dusted with icing sugar.