Step 1: Prepare the Crust

1. Preheat your oven to 350°F (175°C).
2. Combine the crushed biscuits with melted butter in a bowl. Mix until the crumbs are evenly coated and resemble wet sand.
3. Press the mixture firmly into the bottom of a 9-inch springform pan to form an even crust. Use the back of a spoon or the bottom of a glass to pack it tightly.
4. Bake the crust for 8-10 minutes, then let it cool completely.

Step 2: Make the Cheesecake Filling

1. In a large bowl, beat the cream cheese and sugar with an electric mixer until smooth and creamy.
2. Add the eggs, one at a time, mixing on low speed after each addition. Scrape down the sides of the bowl as needed.
3. Mix in the vanilla extract and sour cream until just combined. Avoid overmixing to prevent air bubbles.
4. Pour the cheesecake batter over the cooled crust, smoothing the top with a spatula.

Step 3: Bake the Cheesecake

1. Place the springform pan on a baking sheet to catch any drips.
2. Bake at 325°F (160°C) for 50-60 minutes, or until the edges are set and the center is slightly jiggly.
3. Turn off the oven and leave the cheesecake inside with the door cracked open for 1 hour to cool gradually.
4. Once cooled, refrigerate the cheesecake for at least 4 hours or overnight.

Step 4: Prepare the Caramel Layer

1. In a medium saucepan, heat the sugar over medium heat, stirring constantly, until it melts into a smooth amber liquid.
2. Add the butter and whisk until fully incorporated.
3. Slowly pour in the heavy cream, whisking continuously. Be careful, as the mixture will bubble vigorously.
4. Simmer for 2-3 minutes, then remove from heat and stir in the sea salt if using.
5. Let the caramel cool slightly before pouring it over the chilled cheesecake. Spread it evenly and refrigerate until set.

Step 5: Make the Chocolate Ganache

1. Heat the heavy cream in a small saucepan until it begins to simmer (do not boil).
2. Pour the hot cream over the chocolate chips in a heatproof bowl. Let it sit for 1-2 minutes, then stir until smooth and glossy.
3. Allow the ganache to cool slightly before pouring it over the caramel layer. Spread evenly with an offset spatula.

Step 6: Chill and Serve

1. Refrigerate the assembled cheesecake for at least 2 hours to allow the ganache to set.
2. Carefully remove the springform pan and transfer the cheesecake to a serving platter.
3. Garnish with chocolate curls, whipped cream, or sea salt flakes if desired. Slice and serve chilled.