For the best texture, use "Savoiardi" (hard Italian ladyfingers) rather than the soft, sponge-style ones. If your mangoes are very sweet, you can reduce the powdered sugar in the cream. This dish is actually best made 24 hours in advance to allow the layers to set and the biscuits to soften perfectly. Store any leftovers in an airtight container in the fridge for up to 3 days.