Preheat your oven to 350°F (175°C).

In a food processor, pulse Biscoff cookies into fine crumbs and mix with melted butter and sugar until resembling wet sand. Press into a 9-inch springform pan and bake for 10 minutes.

Using a stand mixer, beat cream cheese, corn starch, and sugar until smooth. Add cookie butter, sour cream, and vanilla, mixing until creamy.

Add eggs and yolks one at a time, mixing gently to avoid over-mixing.

Pour the filling into the crust and create a water bath. Bake for 1 hour, then turn off the oven and leave for an additional hour.

Loosen the cheesecake from the springform pan and chill in the refrigerator for at least 8 hours or overnight.

Before serving, drizzle melted cookie butter on top and decorate with whipped cream if desired.