Mash bananas until you have 2 ¼ cups of mashed bananas.
Combine the flour, salt, baking soda, and nutmeg in a large bowl.
In another bowl, cream together the butter and brown and white sugars. Then, add the cinnamon, eggs, vanilla and mashed bananas, stirring until well blended.
Add the banana mixture into the bowl with the flour and stir. Be sure not to over stir.
Pour batter into a pan that has been sprayed with cooking spray.
Insert a trivet and 1 cup of water into the Instant Pot.
Cover your pan with foil then create a foil handle for the pan. You will be placing this under your pan so the handles stick up and you can remove your pan from the Instant Pot.
Seal the lid and set timer to 50 minutes on manual. After 50 minutes, do a quick release on the pot.
Using the foil handles, remove the pan from the Instant Pot. Allow the pan to cool on a baking rack for a few minutes, then remove the banana bread from the pan and allow it to cool further on the baking rack.