• 30g (1oz) unsalted butter
• 30g (1oz) caster sugar
• 10 tomatoes, cut in half lengthways
• A few sprigs of thyme
• Salt and freshly ground black pepper
• 1 sheet ready-rolled puff pastry, cut to fit over a 20cm8in ovenproof frying pan
• 1 free-range egg, beaten

Preheat the oven to 200C/400F/gas mark 6. Melt the butter in an ovenproof frying pan until it begins to foam, then add the sugar and cook until it caramelises to a golden colour. Season the tomatoes with salt and freshly ground black pepper, then add them, cut-side down, to the pan along with a sprig of thyme. Cook for three minutes, and then remove from the heat. Place the pastry over the tomatoes in the pan and press it down lightly. Tuck the edges of the pastry into the pan and brush with the beaten egg. Transfer to the oven and bake for 25 minutes, or until golden and cooked through. Remove from the oven and carefully turn out onto a plate. Allow to cool a little, then cut into slices. Serve each slice on a plate garnished with a handful of watercress.