Preheat oven to 180°C bake.
In a large jug, whisk eggs, milk, sugar and vanilla together until smooth.
Spread butter onto bread, then roughly tear into random shapes. Slice bananas.
Arrange one third of the bread in a large baking dish. Top with one third of the sliced bananas, followed by one third of the chocolate chips. Repeat using remaining bread, banana and chocolate chips to form two more layers.
Pour egg mixture over the top and leave to rest for 10 minutes.
Bake for 45 minutes - 1 hour, until golden brown and set. Dust with icing sugar and serve warm with whipped cream or ice cream.