The night before, place a shallow dish and 6 dessert or sundae glasses in the freezer so they get nice and cold. While they’re chilling, slice 4 of the 6 bananas and whiz them up in a food processor with the yoghurt, cinnamon, honey, raisins and rum until smooth. If you have time before you start blending, you can soak the raisins in the rum first to give them a chance to plump up. If not, don’t worry, you can just whiz the rum up with the rest of the ingredients for some extra flavour. (If your bananas are ripe, you won’t need quite as much honey. However, if they are still a little firm, you will need the full 3 tablespoons.)
Place the smooth banana mixture into the chilled dish from the freezer, and pop it back into the freezer alongside the serving glasses. The ice cream will need about five hours to freeze completely and will be perfect by the next evening.
On the day itself, just before you’re ready to serve the sundaes, grate the chocolate and roughly chop the hazelnuts. Toast the nuts in a dry pan for a few minutes until they are golden. Heat the dulce de leche in a small saucepan until it’s runny and, while it warms up, slice the remaining 2 bananas.
Remove the glasses from the freezer and start with a layer of the thinly sliced banana. Top with a scoop of banana ice cream, drizzle over the runny dulce de leche and finish off with the toasted hazelnuts and grated dark chocolate. Delicious!