Lightly butter the sides of a 9-inch spring form pan. *
Cut out a round of parchment paper fit it into the bottom of the pan.
In a bowl, cream together the sugars, powdered peanut butter, butter, egg and salt.
Fold in the flour, oats, baking soda and mix until everything is incorporated.
Press the mixture into the pan evenly.
Cover the top of the spring form pan with a dry paper towel.
Seal the pan with a piece of aluminum foil.
Pour the water into the bottom of the pressure cooker pot.
Make a foil sling to lift the pan in and out of the pressure cooker.
Place the pan on the trivet and lower into the pot with the foil sling.
Place the lid on the unit and turn to locked position.
Turn the steam vent to sealing.
Press the manual button and adjust the time for 25 minutes.
When the timer has counted down, carefully release the steam.
Use the foil sling and two towels to lift the blondies out of the pot.
Allow to cool for 10 to 15 minutes.
Release the lever on the spring form pan and remove.
Place a plate on top of the blondies and invert.
Remove the parchment paper.
Allow to cool completely before icing with the frosting.