Preheat oven to 180°C (350°F).
Place the bananas in a bowl and mash with a fork.
Add the oil, eggs, sugar and vanilla and mix to combine.
Add the flour and cinnamon and mix to combine.
Pour into a 22cm round cake tin lined with non-stick baking paper.
Cook for 45 minutes or until a skewer comes out clean.
Alternatly Bunt cake tin for 35 minutes, or until a skewer comes out clean.
Allow to stand in the tin for 5 minutes before turning out onto a wire rack to cool completely.
