Preheat the oven to 200C/400F/Gas 6.
Heat the butter in a small ovenproof frying pan, add the sugar and cook until the sugar has melted and caramelised. Add the apple slices and stir to coat them in the caramel.
Cut a circle of puff pastry to fit over the frying pan. Place the pastry circle on top of the apples and push down around the edges to seal in the apples.
Transfer to the oven and bake for 8-10 minutes, or until the pastry is golden-brown and risen. Remove from the oven and allow to cool slightly.
To serve, carefully turn the tarte tatin out onto a plate and pour over the cream.