Warm the milk and add the dates, letting them soften for a few minutes, then blend until smooth
In a separate bowl, mash the bananas with the eggs, then combine with the warm date-milk mixture
Gently fold in the dry ingredients — flour, cocoa powder, baking powder, baking soda, and vanilla — until just combined
Stir in most of the chopped chocolate and walnuts, reserving some for the top
Pour into a lined baking tin and sprinkle the remaining chocolate and walnuts over the surface
Bake at 170°C for around 50 minutes (cover around the 30th minute if it darkens too much on top)
Let cool slightly before slicing and enjoying
