Place 1 cup water and trivet inside instant pot.

Grease a 7-inch push pan with butter and flour and set aside.

In a large bowl, whisk together the flour, sugars, baking soda, salt, and cinnamon.

In a medium bowl, whisk together the eggs, butter, buttermilk, and vanilla.

Make a well in the center of the dry ingredients and mix in the wet ingredients, just until combined. The batter should still be lump with a few dry spots.

Fold in the mashed banana.

Pour the prepared batter into greased cake pan.

Place a paper towel over the top of the pan and wrap the top of the pan tightly with foil.

Use the trivet (if handles are long enough) or foil sling to lower pan into isntant pot.

Close the lid and set the pressure release valve to sealing.

Press the manual or pressure cook button and set to 65 minutes on high pressure.

Natural pressure release.

Gently remove the pan and remove the paper towel and foil.

Let the banana bread cool on a cooling rack.

Remove from pan and serve.

Store in the refrigerator up to three days.