Preheat your oven to 325°F (160°C). In a bowl, combine the graham cracker crumbs, melted unsalted butter, granulated sugar, and a pinch of salt, mixing until it resembles damp sand. Firmly press this mixture into the bottom of a 9-inch springform pan. Bake for 8-10 minutes or until slightly golden, then allow it to cool completely.

In a large mixing bowl, beat the cream cheese until smooth and fluffy. Gradually add in the granulated sugar and mix until combined. Incorporate the sour cream, vanilla extract, salt, and cornstarch. Blend until fully integrated, then add the eggs one at a time on low speed, ensuring a silky cheesecake mixture.

Carefully pour the cheesecake batter over the cooled crust, smoothing the top with a spatula. To create a water bath, wrap the springform pan in aluminum foil and place it in a larger baking dish filled with hot water. Bake for 50-60 minutes or until the edges appear set and the center jiggles slightly.

Once baked, turn off the oven and leave the door slightly ajar, allowing the cheesecake to cool in the oven for 1 hour. Then remove it from the oven and cool to room temperature. Refrigerate for 4-6 hours, preferably overnight.

In a saucepan, heat the whole milk over medium heat until steaming. In a separate bowl, whisk together the egg yolks, granulated sugar, cornstarch, and a pinch of salt. Gradually whisk in the hot milk to temper the yolks, then return the mixture to the stovetop. Cook, stirring constantly, until thickened, about 5-7 minutes. Stir in the unsalted butter and vanilla extract, then chill.

Once the pastry cream has cooled and thickened, spread it evenly over the chilled cheesecake layer. Refrigerate to set for another hour.

In a small saucepan, heat the heavy cream until steaming, then pour it over the chocolate chips in a bowl. Allow it to sit for 1 minute, then stir until smooth. If desired, stir in the butter for added shine. Let the ganache cool slightly before gently pouring it over the pastry cream layer.

Once the ganache is poured, refrigerate the cheesecake until the ganache is set, about 1-2 hours. When ready to serve, run a warm knife around the edges of the pan before releasing it. Slice and serve chilled.