3–4 very ripe bananas (about 325g/11½oz peeled weight), mashed using a fork
1 tsp baking powder
100g/3½oz soft light brown sugar
1 tsp ground mixed spice
50g/1¾oz shelled pecan nuts, chopped (optional)
300g/10½oz self-raising flour
100g/3½oz sultanas
150ml/5fl oz sunflower oil, plus extra for greasing