Tip the biscuits into a food processor or bowl. Blitz or bash using a rolling pin to fine crumbs. Warm the spread in a small pan over a low heat until melted, then cool slightly. Or, melt in a heatproof bowl in short blasts in the microwave.

Whisk the double cream to soft peaks using an electric whisk, then gently fold in the condensed milk, vanilla and crushed biscuits. Pour the mixture into a 1.2-litre loaf tin or freezerproof container, then pour over the melted speculoos spread and gently swirl in using a cutlery knife to create a marbled effect. Cover and freeze for at least 6 hrs, or ideally overnight. Will keep frozen for three months. Remove from the freezer 5 mins before scooping, and serve topped with a sprinkle of sea salt flakes, if you like.