Salted caramel tarte tatin

Method

1. Peel, core and halve the apples. Don’t worry if they turn brown – you won’t notice in the finished tart. Put the sugar in a 20cm ovenproof frying pan (measured across the base) with 50ml water, then melt the sugar slowly over a low heat. Once the sugar has melted, turn up the heat and bubble for 5 minutes or so to give a golden caramel (don’t let it get too dark – see above right).
2. Take the caramel off the heat immediately and stir in the butter – it will foam quite vigorously. Sprinkle the caramel with the sea salt (it will melt into it), then arrange the apple halves on top, cut-side up, so they fill the pan – slice any leftover apple into wedges to fill in the gaps (the apples will shrink as they cook). Put the pan back over a gentle heat, then cook for 5 more minutes. Turn the heat off and let the apples cool completely.
3. Heat the oven to 220°C/fan200°C/gas 7. Roll out the pastry on a floured surface to the thickness of a pound coin, then lay over the cooled apples in the pan. Trim the pastry using the edge of the pan as a guide, then carefully tuck it inside the edge around the apples, making sure they don’t move. Bake for 30 minutes until dark golden and puffed. Remove from the oven, stand for 5 minutes, then carefully invert the tart onto a serving plate.