After trying many different recipes for layered bars with a filling of jam or softened dried fruit, I think I've at last found the perfect recipe for the dough layers. This recipe for Date and Ginger Squares, from Sue Lawrence's book 'On Baking' uses an easy shortbread dough made from equal parts of SR flour and semolina, which makes a really crisp, but melt-in-the-mouth biscuit. I adapted the recipe slightly by adding a little lemon zest to the filling, and adding the stem ginger in pieces, rather than blending it with the rest of the filling.
Filling - 175g dates, roughly chopped to check there are no stones left in
1 tablespoon of ginger syrup from a jar of stem ginger
1 tablespoon honey
1 tablespoon lemon juice
zest of half a lemon
good pinch of ground cinnamon
3 tablespoons water
2 balls of stem ginger, finely chopped
Dough - 175g SR flour
85g caster sugar
For the filling, place all the ingredients except the stem ginger into a small pan and simmer together, for about 10 minutes, until all the liquid is absorbed and the dates soft. Purée with a stick blender or in a food processor, then stir in the chopped stem ginger.
For the shortbread dough, melt the butter and sugar together on a gentle heat until the sugar has dissolved, then tip it over the flour and semolina, and combine well. The mixture will be crumbly, not a smooth dough. Put 2/3 of this mixture into a 8" square shallow baking tin lined with baking parchment, spread evenly and press down firmly.
Spread the filling over the base, leaving a small margin around the edges. Crumble the rest of the shortbread mixture over the filling, then press down lightly with the palm of your hand. There may still be a few gaps where the filling shows through, but this is fine!
Bake at 190C for 25 minutes, until the shortbread is golden brown. Cut into 16 squares as soon as the tin comes out of the oven, but cool completely in the tin before trying to move the squares - they will be too fragile while still warm.
I'll also be using the shortbread recipe in other types of bars - it would be interesting to see how the crisp biscuit stands up to using fresh fruit in the filling, which often produces a 'soggy bottom' result.