Preheat your oven to 350°F (175°C). In a mixing bowl, combine finely crushed Biscoff cookies and melted unsalted butter, stiring until it resembles wet sand. Press into the bottom of a 9-inch springform pan and bake for about 10 minutes. Let cool.

In a medium saucepan over low heat, add granulated sugar and stir until it melts and turns amber in color, about 10-15 minutes. Remove from heat, add unsalted butter, warm heavy cream, and coarse sea salt, mixing until smooth.

In a stand mixer, beat cream cheese until creamy. Gradually add sugar and vanilla extract, mixing well. Add eggs one at a time. Finally, add sour cream, heavy cream, cornstarch, and cooled caramel, blending until silky.

Pour the cheesecake filling onto the cooled crust. Prepare a water bath in a larger baking dish with hot water and bake at 325°F (160°C) for 55-65 minutes until the edges are firm.

After baking, turn off the oven and crack the door. Cool for an hour, then refrigerate for at least 6 hours or overnight. Remove from pan, drizzle with salted caramel, sprinkle sea salt, and slice.