Requires: 13cm x 24cm loaf pan
Preheat oven to 180°C conventional oven (400° Fahrenheit/Gas 6). Grease a 13cm x 24cm loaf pan by lightly buttering the base and sides with margarine or butter. Line the base with baking paper, then lightly butter over the baking paper. Add a heaped tablespoon of 00 flour, then turn and shake the pan to coat the butter in flour on the base and sides of the loaf pan.
Use a fork to mash the overripe bananas in a small mixing bowl. If using frozen bananas as per the tip below, ensure that bananas are completely thawed. Stir the lemon juice into the mashed banana mixture and set aside.
Tip: Don’t throw away overripe bananas. When bananas are too ripe to eat, place them in a plastic bag and freeze. Don’t be turned off by the black banana peel – they are fantastic to chop up and use in smoothies (unthawed), or thawed for use in banana muffins or this banana cake recipe.
Use an electric mixer to beat the margarine (or butter), castor sugar (superfine granulated sugar), brown sugar and vanilla essence into a bowl until pale and creamy. Add the eggs, 1 at a time, beating well after each addition. Add the banana mixture and lemon zest to the butter and sugar mixture. Beat until just combined.
Use a wooden spoon to stir in the flour, one tablespoon at a time. You want to see air bubbles rise to the surface of the cake mixture before adding additional tablespoons of flour. Stir the walnuts and sifted baking powder into the cake mixture until well combined.
Note: 00 is a powder-fine Italian type of flour. It is made from soft wheat varieties, and is frequently used in Italian desserts and pastas. 00 flour is available in most supermarkets, Italian food stores and gourmet delicatessens.
Pour the banana cake mixture into the prepared loaf pan and smooth the surface. Bake for 40 mins or until a skewer inserted in centre comes out clean. Allow the cake to cool in the cake pan for 10 minutes, then transfer to a wire rack to cool completely.
Meanwhile, to make the Vanilla cream cheese icing, place the cream cheese and unsalted butter into a large bowl. Use an electric mixer or hand beater to beat until well combined. Add the icing sugar and vanilla bean seeds (or vanilla bean paste) and mix until just combined. Refrigerate the Vanilla cream cheese icing while the cake is cooking and cooling.
Once the banana cake has completely cooled, transfer to a serving plate. Spoon the Vanilla cream cheese icing into a disposable piping bag fitted with a star nozzle. Pipe the icing, starting from one end and working toward the opposite end until the top of the cake is covered completely. Sprinkle walnuts on top of the Vanilla cream cheese icing. Serve on the same day of baking – buon appetito.