To prepare the caramel: In a medium pot, stir to combine ½ cup water, sugar, corn syrup, and salt.
Cook over medium heat until the mixture reaches a deep golden brown (do not stir).
Remove from the heat. Slowly add heavy cream and stir to combine.
Stir in the butter and set aside to cool.
Transfer ½ cup of caramel to a separate bowl and set aside. Set aside the pot of remaining caramel to cool.
Preheat the oven to 350 F.
To prepare the crust: In a food processor, combine Biscoff cookies, salt, and optional cinnamon, if desired.
Grind to fine crumbs.
Add the melted butter and process to combine.
Spray to coat a 9-inch springform pan with cooking spray, and place over a parchment-lined baking sheet.
Pour the crumbs into the pan and use a small measuring cup to press to coat the bottom and 1 inch up the sides of the pan.
Bake for 8 to 10 minutes until fragrant and crisp. Set aside to cool slightly.
Reduce the oven temperature to 300 F.
To prepare the cheesecake filling: In a clean food processor bowl, process the cream cheese, sugar, and sour cream until combined.
Add 1 egg and process until smooth.
Add the remaining eggs, vanilla, and cornstarch, and process until smooth.
Remove the bowl from the processor and stir in the cooled caramel from the pot until no streaks remain visible.
Pour into the prepared crust.
Bake for about 90 minutes until only slightly jiggly in the center.
Let cool on a wire rack to room temperature, about 1 hour, then wrap and refrigerate for at least four hours or overnight.
Prepare optional toppings: Whip heavy cream and powdered sugar to medium peaks. Spread the over the center of the cooled cheesecake and sprinkle the edges with pecans and sea salt, if desired.
Slices and drizzle with the remaining ½ cup caramel before serving.