1 Place the first six ingredients in a pan and bring to the boil, then lower the heat and simmer, covered, for about 5 minutes or until the dates are soft. Remove from the heat, tip into a small food processor and whizz. Allow to cool.
2 For the shortbread, beat the slightly softened butter and caster sugar together until light and fluffy – about 10 minutes – then gradually add the flour and semolina and a pinch of salt. Combine very briefly, until it just comes together as a dough.
3 Tip two-thirds of this mixture into a buttered, square, 23cm/9in tin, pressing down, then top with the cooled date mixture, spreading it out. Break the remaining shortbread into nuggets and dot all over the dates. Press down lightly with the palms of your hands and bake in a preheated oven (170C/Gas Mark 3) for 30-40 minutes until golden.
4 Remove to a wire rack and sprinkle with the demerara sugar. Cut into squares while hot, then leave until cold before removing from the tin.
• Scottish Baking by Sue Lawrence is out now in paperback, at £12.99, published by Birlinn