Tarte tatin are versatile and unusual in both their sweet and savoury versions, perfect for buffets or as finger food. This is a savoury version, made not with the more common cherry tomato comfit, but with olives and shallots. Peel the shallots, slice them in half lengthways, and sauté them on a medium heat with a spoonful of extra virgin olive oil, cut side up, in a metal oven pan for a few minutes and then sprinkle them with the brown sugar. Turn them over, add a spoonful of balsamic vinegar and lastly a handful of olives. Cover the shallots and olives with puff pastry, trimming the edges. Bake in a pre/heated oven at 180°C for 20/25 minutes, or until the pastry is golden brown. Leave to cool for a few minutes and then turn tarte tatin out onto a serving dish.