Grease an 18cm (7 inch) springform cake tin with butter.
In a large bowl, combine the flour, baking soda, cinnamon and salt.
In a separate bowl, whisk together the bananas, eggs, milk, oil, sugar and vanilla extract.
Fold the wet ingredients into the dry and transfer to the cake tin.
Add the trivet to the instant pot with the cake tin on top.
Put the lid on and set to bake at 160c (320f) for 35 minutes
Remove the lid and the cake. Place on a rack to cool for around 30 minutes.
Serve and enjoy.