1. Prepare the Vanilla Cake Base:

– Preheat your oven to **350°F (175°C)**. Grease a **9-inch springform pan** and line the bottom with parchment paper.

– In a medium bowl, whisk together the **flour**, **baking powder**, and **salt**.

– In a large mixing bowl, cream the **softened butter** and **sugar** until light and fluffy, about **2-3 minutes**.

– Add the **eggs** one at a time, beating well after each addition. Mix in the **vanilla extract**.

– Gradually add the dry ingredients to the butter mixture, alternating with the **milk**. Begin and end with the dry ingredients.

– Pour the batter into the prepared pan and bake for **20-25 minutes**, or until a toothpick inserted into the center comes out clean.

– Allow the cake to cool completely in the pan. Once cooled, remove the cake from the pan, re-grease the pan’s sides, and place the cake back into the pan.

2. Prepare the Cheesecake Layer:

Reduce the oven temperature to **325°F (160°C)**.

– In a large bowl, beat the **cream cheese** and **sugar** until smooth and creamy.

– Add the **sour cream** and **vanilla extract**, mixing until just combined.

– Add the **eggs** one at a time, beating on low speed until just incorporated. **Do not overmix** to prevent air bubbles.

– Pour the cheesecake batter over the cooled cake layer in the springform pan.

3. Bake the Cheesecake:

– Wrap the bottom of the springform pan with **aluminum foil** to prevent water from seeping in.

– Place the pan in a larger roasting pan and fill the roasting pan with **hot water** until it reaches halfway up the sides of the springform pan (**water bath**).

– Bake for **70-80 minutes**, or until the edges are set but the center still **jiggles slightly** when gently shaken.

– Turn off the oven, crack the door open, and let the cheesecake sit in the oven for an additional **hour**.

– Remove the cheesecake from the water bath and allow it to cool completely on a wire rack.

– Refrigerate for at least **6 hours** or **overnight**.

4. Prepare the Pastry Cream:

– In a medium saucepan, heat the **milk** over medium heat until it begins to simmer.

– In a separate bowl, whisk together the **sugar** and **egg yolks** until pale and thick.

– Whisk in the **cornstarch** until smooth.

– Slowly pour the hot milk into the egg mixture while **whisking constantly** to temper the eggs.

– Pour the mixture back into the saucepan and cook over medium heat, stirring constantly, until it **thickens** and comes to a **boil**.

– Remove from heat and stir in the **butter** and **vanilla extract** until smooth.

– Pour the pastry cream into a bowl, cover with plastic wrap **touching the surface**, and refrigerate until completely cooled.

5. Prepare the Chocolate Ganache:

– Place the **chocolate chips** in a heatproof bowl.

– In a small saucepan, heat the **heavy cream** until it just begins to simmer (**do not boil**).

– Pour the hot cream over the chocolate chips and let it sit for **2-3 minutes**.

– Add the **corn syrup** (if using) and stir gently until the mixture is **smooth and glossy**.

– Allow it to cool slightly until it thickens but is still pourable.

6. Assemble the Cheesecake:

– Remove the chilled cheesecake from the springform pan and place it on a serving platter.

– Pour the **chocolate ganache** over the top of the cheesecake, allowing some to drip down the sides for a rustic look.

– Using a piping bag fitted with a large tip, pipe the cooled **pastry cream** onto the top of the ganache layer, or spread it evenly over the top.

– Optional: Garnish with **chocolate shavings** or **fresh berries** for an added touch.

7. Serve and Enjoy:

 – Slice the cheesecake using a sharp knife wiped clean between cuts for neat slices.- Serve chilled and enjoy the decadent layers of cake, cheesecake, pastry cream, and chocolate ganache.