- Preheat the oven to 375 °F. Grease a 9-inch springform pan, wrap the bottom in foil and place the pan in a roasting pan.
- Cut the banana bread into 1-inch cubes and spread them out on an ungreased baking tray. Toast the banana bread until the outsides of the cubes have dried, about 10 minutes. Leave on the tray to cool.
- Heat the milk to just below a simmer and pour it over the chopped chocolate in a bowl. Whisk the mixture until the chocolate has melted.
- In a separate bowl, whisk the eggs, sugar and vanilla. Add the chocolate milk to the eggs while whisking, until evenly blended. Add the banana bread pieces and stir to coat. Let the mixture sit for 10 minutes, stirring occasionally (the banana bread cubes will begin to break up – that is expected). Reduce the oven temperature to 350 °F.
- Pour the mixture into the prepared pan and pour boiling water into the roasting pan so that it comes halfway up the side of the springform pan. Bake the pudding for 60 to seventy minutes, until a tester inserted in the centre of the pudding comes out clean. Let the cake cool to room temperature before chilling in the pan until set, about 5 hours.
The bread pudding is best served chilled.