With a hand mixer or stand mixer beat cream cheese until smooth.
Add in sugar, cornstarch, and salt and mix until combined.
Mix in vanilla and sour cream until combined.
Beat eggs in one at a time until blended.
Fold in melted chocolate.
Pour half of the cheesecake mixture into the crust.
Pour half of the raspberry sauce onto the cheesecake filling. Using a fork or knife carefully make a few swirls to mix together. Just make sure not to hit crust.
Then pour the rest of the cheesecake mixture and then the rest of the raspberry and give it a swirl.
Cover pan with foil.
Add one and half cups to the Instant Pot and place the trivet inside.
Put cheesecake onto the trivet and put the lid on the pot and close the valve to sealing.
Cook on manual/high pressure for 34 minutes.
When done allow for a natural release.
Then remove from the pot and allow it to cool on the counter.
After cooled place in fridge overnight to set up all the way before serving.
Top with fresh cool whip.