Heat the oven to 220C/200C fan/gas 7. Tip the chicory halves into a small roasting tin and drizzle over the vinegar and oil. Toss well to coat the chicory leaves, then season and scatter in the rosemary. Arrange the chicory, cut-side up, in the tin, and sprinkle over the sugar. Roast for 20 mins until the stalks are just tender when pressed with a knife, and the leaves look soft and wilted. Leave to cool while you make the tartlets, then drain off any excess liquid from the tin.

Unroll the pastry sheets onto two baking sheets lined with baking parchment. Cut each into four rectangles, then arrange on the sheets so there’s a little space between them. Score a 1cm border on each rectangle with a blunt knife. Season the crème fraîche, then spoon into the middle of each tartlet, spreading it to the border. Scatter about half the cheese inside the borders of the tartlets, then top each with a chicory half, leaving any juices in the roasting tin. Top with the remaining cheese and bake for 20 mins until the pastry is puffed up and golden, and the cheese is melted and bubbling. Scatter with the pine nuts and bake for another 5 mins until golden and toasted. Leave to cool for 5-10 mins before serving.