Preheat your oven to 350°F (175°C). In a food processor, pulse the Biscoff cookies until finely crushed, then combine them with melted butter and granulated sugar in a bowl. Mix until the crumbs are well-coated, then transfer to a springform pan. Press the mixture firmly into the bottom, ensuring even coverage. Bake the crust for 10 minutes until set, then allow it to cool while you prepare the filling.

In your stand mixer, beat the cream cheese on medium speed until smooth and creamy, about 2-3 minutes. Gradually add the corn starch and sugar, mixing until well incorporated. Next, blend in the Biscoff cookie butter, sour cream, and vanilla extract, mixing just until combined and smooth.

With the mixer on low speed, add the room-temperature eggs and egg yolks one at a time, allowing each to fully blend in before adding the next. Be careful not to overmix.

Pour the cheesecake filling over the cooled crust in the springform pan. Carefully place this pan inside a larger roasting pan and fill it with boiling water halfway up the sides of the cheesecake pan. Bake for 1 hour or until the edges are set but the center still has a slight jiggle. After baking, turn off the oven and let the cheesecake rest inside for an additional hour.

Once the hour is up, remove the cheesecake from the oven and carefully loosen the edges with a knife. Allow it to cool at room temperature before refrigerating it for at least 8 hours or overnight.

After chilling, remove the cheesecake from the fridge and pour melted Biscoff cookie butter over the top, smoothing it evenly with a spatula. Garnish with fresh whipped cream, cookie crumbs, and whole Biscoff cookies before serving.