Step 1

Preheat oven to 160°C/325°F. Grease a 13cm x 24cm (4½in x 8½in) loaf pan (top measurement), (2 litre/8-cup); line base and long sides with baking paper, extending the paper 5cm (2in) over the sides.

Step 2

Beat butter, sugar, syrup, egg and banana in a medium bowl until combined. Fold in sifted flours, then stir in vanilla paste, cinnamon and milk until well combined. Spoon mixture into pan; smooth the surface.

Step 3

Bake for 1 hour (cover loosely with foil if it starts to overbrown) or until a skewer inserted in the centre comes out clean. Leave cake in pan for 10 minutes before transferring to a wire rack to cool.

Step 4

Meanwhile, make passionfruit icing.

Step 5

Spread cold cake with icing.

Step 6

Place sifted sugar, butter and pulp in a small heatproof bowl over a small saucepan of simmering water (make sure the base of the bowl doesn't touch the water); stir for 1 minute, or until icing is spreadable.