Coconut and berry cake bars

Lightly grease a 23cm square cake tin and line with baking parchment. For the base, put the flour, butter and salt into a food processor and pulse to fine crumbs, then pulse in the coconut and sugar. Beat the egg yolk with the vanilla and 1 tbsp cold water, then add to the machine with the motor running, to make a soft dough. Roughly press into the prepared tin with your hands, dust with a little flour and press with the back of a spoon to push into the corners and flatten. Prick with a fork, then chill for 10 minutes. Meanwhile, preheat the oven to 200ºC, gas mark 6.

Bake the biscuit base for 15 minutes, or until pale golden. Cool for a couple of minutes, then spread with the jam. Lower the oven temperature to 180ºC, gas mark 4.

For the cake, melt the butter in a pan, then take off the heat and use a fork to beat in the yogurt, then the eggs and reserved egg white. Sift the flour, salt and baking powder into a large bowl; stir in the sugar and coconut.

Pour the wet cake ingredients into the dry, and mix well with a spatula. Pour over the jammy base, level the top, then scatter with the berries. Bake for 45-50 minutes, until golden and risen all over; a skewer inserted into the middle should come out clean. Cool in the tin, then cut into bars.