In a large mixing bowl mix together crushed Biscoff biscuits and melted butter. Add the biscuit mixture to a cake tin and flatten it with a spatula or the bottom of a measuring cup.
Place it in the freezer for 10 minutes or in the refrigerator for 20 minutes whilst you make the cheesecake filling.
Biscoff Cheesecake Filling
Add mascarpone, Biscoff spread and sugar to a large chilled bowl. Gently fold together the ingredients with a cool spatula until just incorporated.
Add the cheesecake filling into the chilled cake tin. Use a spatula to smooth the surface of the cheesecake. Wrap tightly with cling film and place in the refrigerator to chill for at least 1 hour.
Add Biscoff spread into a microwaveable bowl. Place it in the microwave for 20 seconds and mix, then add for another 10-20 seconds, until fully melted.
Pour the melted Biscoff spread over the chilled cheesecake. Rotate the cake tin in a circular motion until the topping is smooth and covering all the surface.
Cover the cheesecake and place it in the refrigerator for 1 to 2 hours or until the topping has set.
Optionally, decorate the top of the cheesecake. Then use a thin stainless steel spatula/palette knife and gently cut around the edges of the cheesecake. Gently take off the cake tin and serve.
If you're in a hurry and the cheesecake filling is still cool after adding it to the biscuit base. You can skip waiting for an hour and place the cheesecake in the freezer whilst you prepare the topping.