Line a 20 cm square tin with baking paper.

Crush the speculoos biscuits into fine crumbs using a food processor or seal them in a bag and crush with a rolling pin.

Transfer the crumbs to a bowl and mix with the powdered sugar and melted butter until evenly combined.

Stir in 240 g of the speculoos spread until the mixture comes together.

Press the mixture firmly into the lined tin to form an even base, then chill while you make the topping.

Melt the white chocolate in the microwave in 30-second intervals, stirring between each round until smooth.

In a separate bowl, warm the remaining speculoos spread in 20-second intervals until loose and pourable.

Take the chilled base out of the fridge and spread the melted white chocolate over the top in an even layer.

Drizzle the softened speculoos spread over the chocolate, then use a knife or skewer to swirl the two together for a marbled finish.

Refrigerate for at least 2 hours, or until fully set.

Let it sit at room temperature for about 10 minutes before slicing into 16 pieces.