Whisk egg, buttermilk and oil in a medium bowl until combined and lump-free. Stir in cornmeal, flour, sugar, baking powder and salt just until combined.

Tightly wrap aluminum foil outside around the bottom of a 7" springform pan to seal the pan. This prevents liquid from getting in or batter leaking out while cornbread cooks! Spray the inside (bottom/sides) of the springform pan with non-stick baking spray.

Pour cornbread batter into prepared springform pan. Tightly cover the top of the springform pan with more foil, to seal it. You should have tightly wrapped foil on the TOP and BOTTOM of the batter-filled springform pan.

Place trivet on the bottom of the pressure cooker's inner pot; add 1 cup of water. Carefully lower the foil-covered springform pan onto the trivet.

Lock the lid in place; flip pressure release valve to SEALING. Press MANUAL (or HIGH PRESSURE) button; set timer for 55 minutes. It takes 10-15 minutes for the Instant Pot to reach full pressure, then the pressure gauge will pop up, and cooking program will begin. Once done, let pressure release NATURALLY (do nothing) for 10 minutes, then flip pressure release knob to VENTING, to release any remaining pressure/steam. When all steam has been released and pressure gauge drops down, the Instant Pot can be opened safely.

Carefully remove springform pan from the Instant Pot. Wipe excess moisture from the foil on top with paper towels before opening. Remove foil completely. Release latches to remove the sides of the pan. Transfer cornbread to cutting board; let it cool 1-2 minutes before slicing/serving. Enjoy!