Blueberry & lemon shortbread

1. Put the butter in a mixing bowl and beat well with a wooden spoon until pale and fluffy – about 2-3 minutes. Beat in the sugar for another minute, then briefl y beat in the vanilla and lemon zest.

2. Sift in both flours and the salt, then beat into the mixture until just combined (it might be quite crumbly); stir in the blueberries. Bring the mixture together with your hands and shape into a flat disc.

3. Roll out between 2 sheets of baking parchment to about 0.3cm thick; chill for 30 minutes. Preheat the oven to 180˚C, gas mark 4. Peel off the top layer of parchment and stamp out rounds using a 5-6cm fluted biscuit cutter. Lay, well spaced out, on parchment-lined baking trays.

4. Scatter the biscuits with the extra caster sugar and bake for about 8-12 minutes, rotating the trays halfway, until lightly golden; you may need to do this in batches. Transfer to a wire rack to cool completely

Cook’s tip

Rice flour helps to give shortbread its crumbliness (also known as ‘shortness’). If you don’t have any, you can just use plain flour instead.