Crush the biscuits for the base: Place the Biscoff biscuits in a sealed freezer bag and bash them with a rolling pin until they resemble fine sand. You want a uniform crumb — no jagged chunks. The texture should feel like damp beach sand when you pinch it.

Combine with melted butter: Pour the melted butter over the biscuit crumbs and stir with a fork until every grain is coated. The mixture should clump together when pressed between your fingers, feeling slightly greasy but holding its shape.

Press into the tin: Tip the buttery crumbs into a 20cm springform tin lined with parchment paper. Press them down firmly using the flat base of a glass or a measuring cup. The base should feel compact and solid, with no loose crumbs rattling around. Pop it in the fridge to set while you make the filling.

Beat the cream cheese and sugar: In a large mixing bowl, beat the cream cheese with an electric mixer until it's completely smooth and silky — about 2 minutes. You should see no lumps, and the mixture should look glossy and pale. Add the caster sugar and vanilla, then beat for another minute until the sugar has dissolved and the mixture feels light and airy.

Whip the double cream: In a separate bowl, whip the double cream with the icing sugar until soft peaks form. When you lift the whisk, the cream should hold a gentle peak that flops over slightly at the tip. Be careful not to over-whip, or you'll end up with butter.

Fold everything together: Gently fold the whipped cream into the cream cheese mixture using a spatula. Use a figure-of-eight motion, scraping the bottom of the bowl. The batter should be thick, mousse-like, and completely uniform in colour — no streaks of white or yellow.

Layer and swirl the cookie butter: Spread half the cheesecake filling over the chilled base. Warm the Biscoff cookie butter in the microwave for 10–15 seconds until it's runny but not hot. Drop spoonfuls of the warm cookie butter over the filling, then add the remaining cheesecake mixture on top. Use a skewer or a knife to swirl the cookie butter through the top layer — aim for ribbons of brown running through the pale cream. The surface should look marbled, with distinct swirls.

Chill until firm: Cover the tin with cling film and refrigerate for at least 4 hours, but overnight is better. The cheesecake should feel set to the touch — when you gently jiggle the tin, the centre should wobble only slightly, like a firm jelly. The edges should be completely solid.

Serve and decorate: Run a hot knife around the edge of the tin before releasing the springform. Slice with a clean, sharp knife, wiping it between cuts for neat pieces. Top with crumbled Biscoff biscuits or a drizzle of extra cookie butter if you fancy. The slice should hold its shape cleanly, with a creamy, dense texture that melts on the tongue.