In the bowl of a stand mixer equipped with a paddle attachment, add the softened cream cheese and cream on high speed for 3-4 minutes. This is an important step, do not skip it.
When the cream cheese is light and fluffy and there is no lumps, scrape the sides of the bowl and add the granulated sugar and mix for an additional 2-3 minutes.
Scrape the sides and bottom of the bowl and add the cocoa powder and flour. Mix until just combined.
At this point, scrape the sides and bottom of the bowl and make sure there are no lumps of cream cheese in the batter, if there is, mix on high speed for a few additional minutes.
Add in the melted chocolate, heavy cream, and vanilla extract and mix on med-high speed for 2-3 minutes.
With the mixer on low speed, add the eggs in one at a time and mix just until combined. Be careful not to overmix here! As soon as the yolk disappears, stop mixing.
Scrape the sides and bottom of the bowl and make sure everything is combined and smooth.
Pour the batter into the prepared crust and gently tap on the counter to remove any air bubbles.
Cover the springform pan tightly with aluminum foil.
Prepare your Instant Pot by adding 1 cup of water and a trivet into the inner pot. Place the cheesecake on the trivet and place the lid on sealing.
Cook on high for 40 minutes and allow a natural release. Once you can open the lid, remove the cheesecake and allow to cool completely on the counter. (If the cheesecake looks undercooked when you take it out, it is OK! It will set up in the fridge)
Once the cheesecake has cooled to room temperature, place in the refrigerator for at least 6 hours but overnight is best.