Whip the cream and sugar. In a large mixing bowl, pour in the double cream and caster sugar. Using a hand mixer or stand mixer, beat on medium-high speed until soft peaks form. You are looking for the cream to hold a gentle, droopy peak when you lift the beaters — it should look like a thick, pillowy cloud, pale and glossy. The sound of the mixer will change from a sloshing liquid to a softer, muffled beat as the cream thickens.

Fold in the Greek yogurt. Add the full-fat Greek yogurt and vanilla bean paste to the whipped cream. Using a rubber spatula, fold gently with a wide, sweeping motion. Do not stir vigorously. You want the mixture to stay light and airy, not deflated. It will turn a uniform, creamy off-white colour, and the texture will resemble a soft mousse — thick, smooth, and just starting to hold its shape.

Add the chocolate and biscuits. Scatter the roughly crushed chocolate sandwich biscuits and finely chopped dark chocolate over the surface of the yogurt mixture. Sprinkle in the pinch of sea salt. Fold again, but only three or four times — we want streaks of chocolate and pockets of biscuit throughout, not a fully blended grey mess. You should see distinct dark flecks and biscuit chunks suspended in the pale cream.

Transfer to a container. Spoon the mixture into a freezer-safe loaf tin or a 1-litre container. Smooth the top gently with the back of the spatula, but leave it slightly uneven — those peaks and dips will create lovely texture as it freezes. The mixture at this stage is thick but spreadable, like a soft frosting.

Cover and freeze. Press a piece of baking parchment directly onto the surface of the ice cream (this prevents ice crystals from forming). Seal the container with a lid or cling film. Place it on a flat shelf in the freezer and leave it for at least 4 hours, but preferably overnight. After 4 hours, the surface should be firm to the touch, and the ice cream should scoop cleanly without dragging.

Soften before scooping. Remove the container from the freezer and let it sit at room temperature for 5 to 8 minutes before scooping. This allows the ice cream to soften just enough to curl into perfect scoops without cracking. The texture will be creamy, not icy, with tender biscuit pieces that still have a slight crunch.