Brush a pudding basin with a little sunflower oil, then line with cling film. Spoon the ice cream into a food processor (or a bowl if you have a handheld blender). Crumble in the cake or pudding, add the mixed spice and 4 tbsp of the rum, and whizz together until nearly smooth. Stir in the raisins.
Scrape the ice cream mixture into the basin and smooth the top. Cover with cling film and freeze overnight until solid.
Take the pudding basin out of the freezer 15 mins before serving. Turn the pudding out onto a serving plate and peel off the cling film. Mix the caramel sauce and remaining 2 tbsp rum together and warm gently, if you like (it’s still lovely cold). Serve with the Ice cream bombe.