In a medium saucepan, heat granulated sugar over medium heat without stirring until it melts into a deep amber color—about 10 minutes. Add sliced butter and stir until combined. Gradually pour in warmed heavy cream while stirring until smooth. Mix in vanilla extract and salt. Let cool to room temperature.

Preheat your oven to 350°F (175°C). This step is crucial for baking the perfect cheesecake.

Crush the Biscoff cookies in a large mixing bowl until they resemble fine crumbs. Combine them with melted butter, mixing until every crumb is coated. Press firmly into the bottom of a 9-inch springform pan. Bake the crust for 10 minutes, then cool completely.

In a large mixing bowl, beat the cream cheese until smooth. Gradually add granulated sugar and vanilla extract, mixing until well combined. Add eggs one at a time, mixing slowly.

Gently fold in heavy cream, sour cream, and cornstarch into the cream cheese mixture, being careful not to overmix. Fold in two-thirds of the cooled salted caramel sauce until evenly distributed.

Pour the cheesecake filling into the cooled crust, spreading it evenly. Bake for 60-70 minutes, until the edges are set but the center jiggles slightly.

After baking, turn off the oven and leave the cheesecake inside with the door slightly ajar for about an hour.

Once cooled, transfer the cheesecake to the refrigerator and chill for at least 4 hours or overnight.

Before serving, drizzle the remaining salted caramel sauce over the cheesecake and sprinkle with flaky sea salt.