Heat oven to 220°C / 200°C (fan oven) / 430°F / Gas Mark 7. Lay the pastry out on a baking sheet. Pinch up the edges to form a border, pressing firmly into the corners. Prick the centre all over with a fork and pop in the oven for 10-15 mins.

Meanwhile, mix the tuna and sweetcorn in a bowl and season.

Remove the pastry from the oven, pressing the centre down with the back of a fork, as it will have puffed up a bit. Spread the crème fraîche across centre, spoon the tuna mix on top, then sprinkle over the cheese. Bake for 10-15 mins more, until golden, puffed up and cooked though. Sprinkle with chives and cut into quarters.