Lower the oven temperature to 300℉.
In another large bowl, use a microwave to heat heavy cream, chocolate, and espresso powder in the microwave until the chocolate is mostly melted. Whisk until combined. Cool slightly if the mixture is very hot.
Add cream cheese and whisk until completely smooth. This may take a couple minutes, be patient and get out any lumps of cream cheese.
Add egg, sugar and vanilla. Whisk until shiny and smooth.
Pour the batter on top of the crust and tap out any air bubbles.
Bake for 22-25 minutes, until the edges are set and the center is still very jiggly when you gently shake the pan.
Crack open the oven door and leave the cheesecake to cool completely. If you'd like a break, chill the cheesecake now in the fridge and come back later.