Make the Crust:

1. Preheat the oven to 325°F (163°C). Grease a 9-inch springform pan.
2. In a bowl, mix the graham cracker crumbs, sugar, and melted butter until combined.
3. Press the mixture firmly into the bottom of the pan. Bake for 10 minutes, then let it cool.

Make the Cheesecake:

4. In a large bowl, beat the cream cheese and sugar until smooth.
5. Add the eggs one at a time, beating after each addition.
6. Mix in the vanilla extract and sour cream until combined.
7. Pour the batter over the cooled crust and smooth the top.
8. Bake for 45–50 minutes, or until the center is slightly jiggly.
9. Turn off the oven, crack the door, and let the cheesecake cool inside for 1 hour. Then chill in the fridge for at least 4 hours.

Make the Pastry Cream:

10. In a saucepan, heat the milk over medium heat until warm but not boiling.
11. In a separate bowl, whisk together sugar, egg yolks, and cornstarch until smooth.
12. Slowly pour the warm milk into the egg mixture, whisking constantly.
13. Return the mixture to the saucepan and cook over medium heat until thickened.
14. Remove from heat, stir in vanilla and butter, then let it cool completely.

Make the Ganache & Assemble:

15. Heat the heavy cream until steaming (but not boiling), then pour over chopped chocolate. Let sit for 2 minutes.
16. Stir until smooth, then mix in vanilla extract.
17. Spread the cooled pastry cream over the cheesecake.
18. Pour the chocolate ganache over the top, letting it drip down the sides.
19. Refrigerate for 1 hour before serving.