Combine graham cracker crumbs with sugar and melted butter and pat down on the bottom of a 7-inch springform pan sprayed with non-stick cooking spray. If desired, sprinkle peanut butter cup pieces on top of the crumb layer. Line sides of the pan with parchment paper.
Cream together the cream cheese and sugar until smooth and then mix in the eggs one at a time. Mix in the vanilla extract and sour cream until smooth.
Mix in the peanut butter OR set it aside to swirl into the cheesecake.
Pour mixture into springform pan on top of the graham cracker crust.
If swirling the peanut butter into the cheesecake, this is when you will do that.
Run a fork back and forth through the cheesecake several times to remove air bubbles.
Cover with foil.
Place trivet in bottom of pot. Pour two cups of water into the inner pot of the Instant Pot.
Make a sling out of aluminum foil to lower the pan into the pressure cooker.
Close the lid of the Instant Pot and turn to sealing position.
Set for a manual high-pressure time of 35 minutes. When the time has finished, allow for a natural release for 12 minutes before letting out the rest of the steam.
Carefully remove the pan from the Instant Pot. Allow it to cool completely before placing in the refrigerator. Chill for 4 hours or more before serving.