Butter the sides of a 9 inch spring form pan. * See notes
Place a cut out of parchment paper in the bottom of the pan.
In a mixing bowl, combine the sugar, vanilla, butter and eggs.
Stir in the flour, cocoa powder baking powder and salt.
Pour the mixture into the pan and smooth out.
Pour the two cups of water into the pressure cooker pot.
Cover the top of the spring form pan with a dry paper towel.
Cover the pan and the paper towel with aluminum foil and seal tightly.
Make a foil sling to lift the pan into and out of the pressure cooker.
Place the pan onto the trivet and lower both into the pot, using the foil sling.
Place the lid on and close to locked position.
Turn the steam release valve to sealing.
Press the manual button and adjust the time for 25 minutes. * See notes
After the unit has finished cooking and the timer has counted to zero, carefully release the steam. *See notes
Use the foil sling and two towels to lift the brownies 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 brownies and invert.
Remove the parchment paper.
Allow to cool completely before icing with the frosting.