Preheat an oven to 175°C.
Take an 11cm x 21cm loaf pan, line it with baking paper, and lightly grease it with spray oil.
Mash banana with a fork, set aside in a bowl.
Cream butter, castor sugar and brown sugar into a large mixing bowl, until smooth. Add the eggs and vanilla vanilla essence or extract, Mix for 3-minutes with an electric mixer to form a smooth batter, scraping down the edges as necessary.
Sift the all-purpose flour, baking powder, baking soda, cinnamon and AdVital Powder into the mixing bowl, and mix until just combined.
Add the mashed bananas, mix them together for 30 seconds, then add the milk. Mix all the ingredients on low speed until just combine.
Pour the batter into the pre-prepared cake or bread pan and bake for 35–45 minutes (or until a skewer inserted into centre comes out clean).
Remove the bread from the oven, and allow it to cool in the pan for 5 minutes. Turn the bread onto a wire rack to cool for 1 hour (or until completely cool). Cut the bread into slices to serve.