The night before, soak the dates with the bicarbonate soda, spiced rum and boiling water. Cover and leave to soften.
Next day, rub the cold butter into the flour until breadcrumb texture.
Blend the dates (including all the liquid) with 2 of the bananas, egg, vanilla paste, and ginger powder.
Combine the blended mixture into the flour and butter mixture.
Tip into a lined 1lb/450g loaf tin and gently level out.
Cut the 3rd banana lengthwise and place gently on top of the batter without pushing it in.
Sprinkle with the sugar crystals.
Bake at 160°C for an hour, until a skewer comes out clean when inserted.
Leave to cool and slice. Store for up to a week.
