Using a sieve, combine the plain flour, baking soda, baking powder, cinnamon and salt in a mixing bowl.
In another bowl, mash the bananas and mix with the beaten eggs and vanilla extract.
In a third bowl, mix together the butter, coconut oil and sugar until smooth.
Add the butter/oil/sugar mixture to the bowl of banana/egg mixture and stir until just combined.
Carefully pour this on to the bowl of dry ingredients and fold together using a
spatula. Don't overmix!
Pour the cake mix into a cake tin (if using a metal tin, be sure to line with baking paper) and then cover the top with kitchen foil.
Add 250ml water to your Instant Pot, add the trivet and place the cake tin on top.
Close the lid, and turn Venting Knob to Sealing position. Pressure cook at High Pressure for 60 minutes, then allow for 15 mins Natural Release.
Remove the cake tin from the Instant Pot and allow to cool before slicing.