Heat half the sugar in a light coloured, dry frying pan until it starts to melt, without stirring. Give the pan a gentle toss occasionally.
Add the rest of the sugar and bring it to a melted deep amber colour, without burning. Add the butter a little at a time and stir it vigorously until combined. Add salt and vanilla, and finally banana. Cook down the bananas a little. Store in an airtight container in the fridge until use on ice-cream, porridge, pancakes, waffles or as a pie filling. YUMMERS.