Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4 and grease and line a 12" x 9" traybake tin
Use a food processor to make fine crumbs out of the biscuits. You could also crush them in a bowl or ziploc bag with a rolling pin
Add the melted butter to the biscuit crumbs and mix well. Press the mixture into the lined tin until it is compact and even
To make the vanilla cheesecake, whisk together the cream cheese, caster sugar, eggs, and vanilla extract, using an electric whisk or stand mixer, until smooth
To make the Biscoff cheesecake, whisk together the cream cheese, caster sugar, eggs, and Biscoff spread, using an electric whisk or stand mixer, until smooth
Pour the vanilla filling over the biscuit base, then add spoonfuls of the Biscoff filling all over. Use a butter knife to swirl it around and create a pretty pattern
Bake for 30 minutes or until it has set fully and only has a slight wobble. Leave to cool fully, then chill in the fridge
To serve, cut into squares. Keep any leftovers in the fridge for up to 3 days