Method

• 1.
  Place the biscuits and cocoa powder in a food processor and process until the mixture resembles fine crumbs. Add the butter and process to combine. Use the mixture to line a greased 27cm pie dish. Refrigerate.
• 2.
  Place the milk and the vanilla bean in a saucepan and bring to the boil. Set aside for 30 minutes to infuse. Remove and discard the vanilla bean.
• 3.
  Beat together the egg yolks, sugar and cornflour in a bowl. Pour the infused milk over the eggs, then return to the saucepan. Cook over low heat for 5-6 minutes, stirring occasionally, until thick. Pour into a bowl. Set aside to cool over iced water.
• 4.
  Whip the cream and fold into the mixture. Transfer to freezer for 30 minutes until it begins to thicken.
• 5.
  To make the raspberry sauce, place the sugar and 2 tablespoons water in a small saucepan over medium heat, stirring to dissolve the sugar. Set aside to cool slightly, then add the raspberries and lemon juice. Transfer to a food processor and process until smooth. Pass through a sieve.
• 6.
  Pour the ice-cream mixture into the pie dish and use a knife to make ridges. Pour some of the sauce into the ridges, then swirl to form a pattern. Freeze overnight.
• 7.
  Transfer to the fridge for 30 minutes before serving. Serve the pie with the remaining raspberry sauce drizzled over the top.