Add the cream cheese, sugar, flour, nutmeg, and salt to a mixing bowl and beat with an electric mixer until smooth and creamy.
Add the eggs, one at a time, and mix by hand with a wire whisk. Be careful not to over-whisk and incorporate too much air into the batter, to avoid cracks in your cheesecake.
Add in the eggnog and vanilla extract and mix with a spatula until combined.
Pour the batter into the prepared crust. Tap the pan gently on a table or kitchen counter to remove any air bubbles. Cover with aluminum foil.
Pour 1 cup of cold water into the liner of the pressure cooker and put in the trivet. Place the cheesecake onto the trivet. Use a foil sling to make it easier to insert and remove the cheesecake, if desired.
Close the pressure cooker and set the valve to the “seal” position.
Pressure cook on “high” for 50 minutes and then allow the pressure to release naturally for 20 minutes.
Quick release the remaining pressure and open the lid.
Carefully remove the cheesecake from the Instant Pot and remove the foil.
Gently blot any liquid off the top of the cheesecake with a paper towel.
Cool the cheesecake on the counter for 1 hour and then cover with plastic wrap and refrigerate for at least 6 hours or overnight.