Preheat the oven to 150°C/Gas mark 2. Cut each pain au chocolat into three equal pieces widthways and pack them into a baking dish.
Mix the milk and cream in a saucepan and bring to the boil. Add the chocolate and stir until smooth.
Mix the sugar and eggs in a bowl and pour the chocolate mixture over, whisking constantly. Then slowly pour the custard over the pain au chocolat, allowing the custard to be absorbed before adding more.
Bake 25-30 minutes or until the top is lightly crisp but the centre is still wobbly. Serve warm with cream or ice cream.