Place a 10-inch ovenproof heavy-based frying pan over medium heat and melt the butter. Add the sugar and the cinnamon and stir often until de mixture turns syrupy.
Then, peel and cut the apples. It may seem a bit laborious, but, believe me, it’s done in five minutes. To do the job, use a vegetable peeler, a fruit core remover and a knife. First, peel the apples, then core them, and finally, halve them.
Put them upside down in the pan, on top of the caramel. Bear in mind, that the side you put down is the side that will show once the tart is finished.
Cook the apples for about 10-15 minutes, until tender.
Roll out the puff pastry and cut out a circle about the same size as the top of the pan. Cover the apples with the pastry and tuck it around the apples.
Transfer the pan to the oven and bake for 25-30 minutes. Remove from the oven and let cool for about 10 minutes.
Inverting the tart is the only tricky part, although I have to say that I have never had a bad experience myself. Using oven globes and inverting the pan together with the serving plate in one swift movement, guarantees success.
And now, it is time to enjoy the fruity and caramelized tart! Serve at room temperature or slightly warm with some vanilla ice cream.