Preheat oven to 170 C. Grease and flour a 22cm loose-bottomed cake tin.

Put sultanas and liquid in a saucepan and bring to the boil. Simmer for 10-15 minutes, until the sultanas are plump and swollen. Remove from the heat and allow to cool, then drain off any remaining liquid. Mix all the dry ingredients in a medium bowl. In a large mixing bowl, beat the melted butter and maple syrup with a hand beater until well blended. Beat in the eggs, one at a time, with a wooden spoon, then add the mashed bananas. Stir in the drained sultanas and vanilla extract. Fold in the flour mixture, a third at a time, stirring well to combine each addition before adding the next. Scrape the mixture into the prepared tin, level the top with the back of a spoon and bake for one hour, or until a skewer inserted into the centre comes out clean. Remove from the oven and leave to cool for 10 minutes before turning out onto a wire rack to cool completely.