In a mixing bowl, combine graham cracker crumbs and melted butter until it resembles wet sand. Press the mixture into the bottom of a springform pan to create a solid crust. Pop it into the oven at 350°F (175°C) for about 8 minutes.

While the crust cools, beat the softened cream cheese and sugar together until smooth. Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract and sour cream. Pour it onto the cooled crust and smooth the top.

Bake your cheesecake in the oven for about 50-60 minutes, or until the center is slightly jiggly. Once it’s ready, turn off the oven and let it cool in the oven with the door ajar.

In a small saucepan, whisk together sugar, egg yolks, and cornstarch. Slowly add in the milk while constantly whisking to prevent lumps. Cook over medium heat, continuing to whisk until it thickens. Once thick, stir in vanilla extract, and let it cool.

In another saucepan, heat heavy cream until just simmering. Pour over the chocolate chips in a bowl and let it sit for a minute. Stir until completely smooth.

Spread the cooled pastry cream over the cheesecake layer, then drizzle with the chocolate ganache on top. Chill in the refrigerator for at least 4 hours, or overnight.