Mix together the butter and sugar. You don't want to cream the mixture together just mix it for around 1 minute or so until it forms lovely buttery nuggets.
Add in the egg, vanilla, self-raising flour, and bicarbonate of soda and mix again until just combined. This should only take around 30 seconds to 1 minute.
Finally add in the chocolate chips and crushed Biscoff biscuits and mix again until they are evenly distributed. The mixture should resemble thick cookie nuggets.
Roll the dough into 8 cookie balls weighing around 125g each. Gently press the balls together then press your thumb into the centre of hte cookie. Add, a blob of Biscoff to the centre and press the cookie dough around the spread.
Place the cookie balls into a airtight container on on a baking sheet and pop them into the freezer for 1 hour.
Before the 1 hour is up, preheat the oven to 180 (160C Fan) and line two baking trays with baking parchment.
Once your oven is preheated, place the cookies on the baking tray make sure that they are evenly spaced out as thye will spread in the oven.
Bake in the oven for 12-15 minutes.
Once the cookies have baked, leave them to cool for 15-20 minutes on the baking sheet before transferring them onto a wire rack to cool fully.