Prepare the Crust: Preheat your oven to 325°F (160°C). Grease a 9-inch springform pan thoroughly to avoid sticking. In a mixing bowl, combine 2 cups Biscoff cookie crumbs with 1/2 cup unsalted butter, melted. Stir until the mixture is moist and resembles wet sand. Press it firmly into the bottom of the prepared pan to create an even layer. Bake for 10 minutes, then remove from the oven and let it cool.
Make the Cheesecake Filling: In a large bowl, using an electric mixer, beat 24 oz cream cheese, softened until smooth and creamy. Gradually add 3/4 cup granulated sugar and 1/4 cup brown sugar; mix until well combined. Add 3 large eggs one at a time, ensuring each one is fully incorporated before adding the next. Then, blend in 1/2 cup sour cream, 1/4 cup heavy cream, and 1 tsp vanilla extract until just combined. Be careful not to overmix as this can lead to cracks in your cheesecake.
Assemble and Bake: Pour the filling evenly over the cooled crust in the springform pan. Wrap the outside of the pan with aluminum foil to prevent water from seeping in. Place the pan into a roasting dish and fill the dish with hot water halfway up the sides of the springform pan. Bake for 55–65 minutes until the center is set but slightly wobbly. Once baked, turn off the oven, crack the door open, and let the cheesecake cool in the oven for 1 hour to prevent it from cracking.
Chill: Allow the cheesecake to cool to room temperature. Once cooled, cover it with plastic wrap and refrigerate for at least 6 hours, preferably overnight, to let the flavors meld together.
Make the Salted Caramel Sauce: In a medium saucepan, cook 1 cup granulated sugar and 1/4 cup water over medium heat, swirling occasionally until the sugar dissolves and turns a deep amber color (about 10 minutes). Once at the desired color, carefully whisk in 1/2 cup heavy cream, warmed (the mixture will bubble vigorously). Once combined, stir in 3 tbsp unsalted butter and 1/2 tsp flaky sea salt. Allow it to cool before using.
Decorate and Serve: Remove the cheesecake from the springform pan gently. Pour the cooled salted caramel over the top, allowing it to drip down the sides. Garnish with a sprinkle of flaky sea salt and crushed Biscoff cookies for an extra touch. Slice into pieces, serve, and enjoy the decadent flavors!