Linzertorte

Mix the sugar and the lemon zest together.
Add the butter, eggs and cinnamon and beat well.
Stir in 15 ml cold water, almonds and a pinch of salt.
Add the cocoa powder and enough cake flour to make a soft dough, reserving a little for dusting the surface later.
Cover with plastic wrap and place in the fridge until firm.
Once the dough is firm, divide in half and roll one half out on a lightly floured surface.
Work quickly and do not handle the dough too much, because it will become difficult to work with if it gets warm.
Cut out a round and place in a greased 20 cm baking tin.
Spread with half the jam.
Roll out remaining bits of dough again and cut into strips.
Arrange on top of the jam in a crisscross pattern.
Cut longer strips for around the sides of the tart.
Repeat with remaining ingredients to make another tart.
Mix egg yolk with a little water and brush over the pastry.
Sprinkle with a little castor sugar and bake in a preheated 180 degC oven for 30 to 40 minutes until pastry is crisp and golden.
The flavour of the tart improves after a couple of days.