Mix the crushed Biscoff biscuits with the melted butter, then press this mixture firmly into the base of your chosen tin. Place it in the fridge to chill while you prepare the filling.
In a bowl, combine the double cream, full fat cream cheese, and Biscoff spread. Whisk the mixture vigorously until it thickens and holds a shape similar to soft ice cream—using an electric whisk will make this step easier.
Take the chilled biscuit base out of the fridge and evenly spread the creamy cheesecake mixture over it, smoothing the surface with a spatula.
Refrigerate the cheesecake for a minimum of 3 hours, though letting it set overnight will improve the flavor and texture.
Just before serving, gently warm the remaining Biscoff spread in a pan on low heat, taking care not to overheat it.
Remove the cheesecake from the fridge and, while still in the tin, carefully pour the melted Biscoff spread over the top. Use the back of a spoon to smooth it out without disturbing the cheesecake layer. Sprinkle the reserved crushed biscuits around the edges for a decorative finish.
Return the assembled cheesecake to the fridge for at least another hour if possible to let the topping set nicely. While you can slice it sooner, the edges will be cleaner if you wait.
