Beat the room temperature cream cheese and sugar until just creamy.
Add the eggnog, vanilla, cinnamon and nutmeg and beat until just combined.
Add the eggs, one at a time, mixing in between until just combined. Do not over mix.
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 30 minutes, then do a 15 minute natural release.
Do a quick release to release the remaining pressure. When pin drops, remove lid, and using oven mitts, carefully remove the cheesecake from the pot by lifting handles .
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 whipped cream, eggnog whipped cream and a dusting of ground nutmeg, if desired