Pre-heat your oven to 325°F.
In the bowl of a stand mixer, beat together the cream cheese, peanut butter, and sugar until fluffy.
Add the sour cream, eggs and vanilla and beat until smooth.
Pour the mixture over your chilled ganache layer.
Bake for 75-90 minutes until the edges of the cake appear set, but the middle 2-3 inches is still slightly jiggly.
Turn the oven off, crack the door open a bit and leave the cake to cool in the oven for about an hour. Transfer the cake to a wire rack to finish cooling to room temperature. Once the cake has reached room temperature, you can cover it and put it in the fridge.