for the pastry base
175g plain flour, plus extra for dusting
Pinch of salt
50g icing sugar
100g unsalted butter, chilled, cut into small pieces, plus extra for greasing
Finely grated zest of 1 lemon
1 medium free-range egg yolk
1½ tsp lemon juice
for the topping
125g unsalted butter, softened
125g golden caster sugar
Finely grated zest of 1 large lemon
2 large free-range eggs, lightly beaten
25g self-raising flour
175g ground almonds
150g blackberry jam, homemade or shop-bought
35g flaked almonds
1. Preheat the oven to 180°C/fan 160°C/gas 4. For the pastry base, sift the flour, salt and icing sugar into a food processor. Add the butter and lemon zest, then pulse briefly until the mixture looks like fine breadcrumbs. Transfer to a mixing bowl. Lightly beat the egg yolk with the lemon juice, then stir into the flour mix until it comes together in a ball. Turn out onto a lightly floured surface, then knead until smooth.
2. Grease and line a 21cm x 30cm shallow tin with baking paper. Roll out the pastry to a rectangle of the same size, then use to line the base of the tin. Prick all over with a fork, then chill in the fridge for 20 minutes.
3. Bake the pastry for 15 minutes until golden, then remove and set aside to cool slightly.
4. For the topping, put the butter, golden caster sugar and lemon zest into a mixing bowl, then cream together with an electric hand mixer until pale and fluffy. Gradually beat in the eggs, then fold in the flour and ground almonds.
5. Spread the jam evenly over the pastry base, then carefully spread the almond mixture on top. Scatter over half the blackberries, then gently press them into the mixture. Scatter over the remaining berries.
6. Bake for 10 minutes, then remove and swiftly scatter over the flaked almonds. Return to the oven as quickly as you can, then bake for a further 35 minutes until richly golden and an inserted skewer comes away clean. Leave to cool, then remove from the tin and slice into bars.