Beat the room temperature cream cheese and sugar until creamy.
Add the peanut butter and vanilla, and beat until combined.
Add the eggs, one at a time, mixing in between until just combined. Or, beat eggs slightly in separate bowl, and mix in until combined
Pour the cheesecake filling onto the crust, smoothing out with a spatula if necessary.
Pour 1 cup of water into the inner pot of the Instant Pot (6 qt). Place a trivet in the bottom.
If your pan does not have a handle, create a foil sling, place the pan in the sling, then place the sling in the pot. Skip this step if your pan has a handle.
Close the lid and place the valve in the SEALING position. Hit PRESSURE COOK for 50 minutes, then do a 10 minute natural release.
Do a quick release to release the remaining pressure. When pin drops, remove lid, and carefully remove the cheesecake from the pot.
The cheesecake is done when only the center jiggles slightly when you shake the pan back and forth and when its internal temperature is 150 degrees Fahrenheit. If it is not done yet, let it cook for another 5 minutes.
Take the corner of a paper towel and soak up any water on the top of the cheesecake.
Allow the cheesecake to cool slightly before covering. Store covered in the fridge for 4 hours to overnight (recommended) before serving. Top with ganache and mini peanut butter cups if desired