Grease and flour bundt pan - I use cooking spray and a couple T flour to evenly coat the inside of bundt pan to ensure cake does not stick
In medium sized mixing bowl, whisk all dry ingredients (properly measured flour, salt, cinnamon, baking soda, baking powder). Set aside.
In large mixing bowl, using electric mixer, blend oil, butter, sugars and vanilla until very well combined, about 45 seconds on medium speed. Scrape all sides and bottom of mixing bowl.
Add both eggs, blend until just combined, about 10-15 seconds on medium speed.
Add milk and banana; mix until combined, about 20-30 seconds on medium speed. Scrape all sides of mixing bowl
Add dry ingredients, and mix on low speed until just combined, perhaps 20 seconds.
DO NOT OVER-MIX!
Add optional mix-in, if desired.
Optional Mix-ins (1/2 cup of mix in of your choice): cinnamon chips, chocolate chips, walnuts, pecans, shredded coconut
Mix very lightly to avoid over-mixing batter.
Pour batter into greased and floured bundt pan
Cover bundt pan with foil
Add water to pressure cooker insert. Place bundt pan over water in Instant Pot on trivet using trivet handles, or create a foil sling.
Close lid and close vent knob, then set cook time to 47 minutes on High Pressure.
When cook time has completed, allow pressure cooker to naturally release pressure for 5 minutes, then release remaining pressure and remove lid.
Remove foil and allow Banana Bread Cake to cool for about an hour.
Serve as desired, with icing or powdered sugar or plain - it is incredibly delicious as is!