Crush Biscoff cookies to fine crumbs in a food processor. Add melted butter and stir until every crumb is coated and mixture clumps when pressed. Press firmly and evenly into the base of a lined 23cm springform pan. Refrigerate 20 minutes.
Beat room-temperature cream cheese with a mixer on medium speed for 60 to 90 seconds until completely smooth. Add sifted icing sugar and vanilla, beat 30 seconds. Add Biscoff spread and beat until the filling is uniform pale caramel in color with no white streaks.
In a separate bowl, whip cold double cream on medium-high until stiff, straight-standing peaks form. Fold into cream cheese mixture in two additions using a rubber spatula with gentle circular motions until completely combined and smooth.
Pour filling over the chilled base and smooth the top flat with an offset palette knife. Cover and refrigerate for a minimum of 8 hours, ideally overnight.
The next day, microwave the topping Biscoff spread for 15 to 20 seconds until pourable. Stir once and immediately pour over the chilled filling surface, tilting the pan to spread evenly. Scatter crushed Biscoff cookies across the surface while the topping is still tacky. Refrigerate 20 to 30 minutes until the topping is fully set.
Run a thin knife around the inside edge of the springform, unclip the ring, and transfer the cheesecake to a serving plate. Slice with a warm, dry knife for clean edges.
