Use an electric mixer to beat cream cheese and peanut butter smooth, and no clumps remain. Then mix in sugar, cornstarch, and flour until well combined.
Next beat in sour cream, heavy cream, and vanilla.
Finally, break eggs in a bowl and pierce yolks with a fork or toothpick a few times. Stir eggs into cream cheese mixture, stirring as little as possible to incorporate eggs.
Pour batter over crust. If batter does not fully cover crust, remove the crust that you can see (any crust over the batter will get soggy).
Place 1 cup of water in the bottom of Instant Pot. Place pan on metal Instant Pot rack and lower into base. Cook on high pressure for 36 minutes. Let natural release for 20 minutes.
Allow cake to cool at room temperature for 1 hour, the transfer to refrigerator for at least 6 hours before serving.