• Preheat oven to 140°C (convection with fan). Grease and line a 450g/1 lb loaf pan with parchment paper, ensuring the two sides overlap the pan.
• Separate 2 eggs into whites and yolks.

THERMOMIX METHOD

• Insert butterfly whisk into TM mixing bowl - ensuring both whisk and TM mixing bowl are both very clean! Place 2 egg whites in, then without MC, whisk 3 min/speed 3.5 until stiff peaks form, watching carefully to avoid over-whisking. Remove butterfly whisk. Transfer meringue to a bowl and set aside.
• Without cleaning bowl, place banana pieces in mixing bowl and mash 6 sec/speed 5.
• Add 1 whole egg, 2 reserved egg yolks, oil, vanilla extract and milk then mix 20 sec/speed 4.
• Add sugar, flour, baking powder, salt, chocolate chips, any chopped nuts if using, bicarbonate of soda and cocoa powder then mix 15 sec/speed 4.
• Using a spatula, add ⅓ of egg white meringue into the batter to loosen the mixture and fold in lightly. You'd want to be as gentle as you can so as to ensure you do not deflate the egg whites too much. Then add the remaining meringue and fold in to incorporate completely.
• Transfer to prepared tin and bake for 1 hour 15 mins, or until a skewer inserted in the center comes out clean. Leave to cool in the tin for 15-20 minutes on a wire rack. Carefully unmould cake onto a cooling rack to let cool completely.

CONVENTIONAL METHOD

• In a large bowl, sift together the flour, baking powder, bicarb soda, and cocoa powder. Then place remaining dry ingredients (sugar, salt, chocolate chips and chopped nuts if using) in and whisk to combine.
• Mash bananas in another bowl and stir in the whole egg plus 2 yolks, followed by vanilla extract, oil and milk.
• Using a stand mixer with balloon whisk attachment, beat egg whites until stiff peak. When you lift your whisk, your egg white meringue would stand straight up with the tip slightly bent over. Ensure to check the bottom of the bowl to ensure that there is no liquidy mixture as this is considered under-beating.
• Quickly stir the wet banana mixture into the dry ingredients. Then using a spatula, add ⅓ of egg white meringue into the batter to loosen the mixture and fold in lightly. You'd want to be as gentle as you can so as to ensure you do not deflate the egg whites too much. Then add the remaining meringue and fold in to incorporate completely.
• Transfer to prepared tin and bake for 1 hour 15 mins, or until a skewer inserted in the center comes out clean. Leave to cool in the tin for 15-20 minutes on a wire rack. Carefully unmould cake onto a cooling rack to let cool completely.