- Preheat oven to 325°F. Lightly grease a 9-inch springform pan. 
- In a small bowl, mix the graham cracker crumbs, sugar, and melted butter. Press into the bottom of the prepared pan. Bake for 10 minutes and let cool. 
- In a large mixing bowl, beat the cream cheese until smooth. Add sugar, flour, espresso powder, and vanilla. Mix until well combined. 
- Add eggs one at a time, mixing on low after each addition. Stir in the melted chocolate. 
- Pour the filling into the crust. Bake for 55–60 minutes, until the center is almost set. Let cool in the oven with the door cracked open for 1 hour. 
- Mix sour cream and heavy cream. Spread over the cooled cheesecake and chill at least 4 hours or overnight. 
- Garnish with chocolate curls before serving, if desired.