Find the best quality gingernuts you can for this recipe. When paired with the caramel and creamy ice-cream,you need biscuits with a strong hit of ginger so the flavour still sings and shines despite all the competition. I went rogue from the supermarket frozen aisle to my local ice-cream shop and this cake was all the better for it – the caramel was brilliantly salty and while I have suggested white chocolate below,a condensed milk flavour is also particularly excellent.