Lower oven heat to 325.
In a food processor or in a stand mixer, blend the cream cheese with the sugar and salt on high until it is utterly lump-free and completely smooth. Add the vanilla and scrape down the bowl and process for another minute.
Add the pistachio butter and process until it is very smooth and well-blended. Scrape down the bowl and process again to ensure all is combined.
Add the sour cream and process until combined.
Add the eggs, pulse until they are just incorporated.
Pour batter into the crust, and place it in a 13x9" cake pan. Fill the pan halfway with water. This is the water bath.
Bake for about 50, rather than relying on time here look for visual cues for doneness: if it’s set on the sides and jiggly in the center it’s done. If the crust is browning, it's overdone.
Shut the oven off and put a wooden spoon in the door to crack it open. Let the cheesecake cool in the oven for 30 minutes.
Once 30 mins has passed, close the oven door and leave the cheesecake for another 15 minutes.
Remove and cool on the counter for about half an hour.
Transfer to fridge and let cool for 8 hours before serving.