parmesan or Grana Padano or vegetarian alternative e) 100g,
sage ½ a small bunch,
pick 10 small leaves then chop the rest
Cut the squash into paper-thin slices on a mandoline or in a food processor.
Heat the oven to 190C/fan 170C/gas 5. Roll out the pastry to the thickness of a 20p piece then trim to fit an oiled baking sheet.
Mix the mascarpone, parmesan, chopped sage and season. Spread all over the tart leaving a 3cm border. Arrange the squash slices on top, overlapping them very slightly and leaving a 11/2 cm border. Fold the borders of the pastry over so they are touching the squash. Brush with beaten egg.
Season, then bake for 30 minutes until the pastry is crisp and golden and the squash tender.
To finish, heat a knob of butter in a small pan. Add the sage leaves and sizzle until crisp and the butter is golden. Drizzle over the tart and serve just warm.