Preheat the oven to
180°C/350°F/Gas mark 4.
Grease a shallow 25 x
30cml/10 x 12in tin and line with greaseproof paper.
Put the dates, sugar,
butter and lemon zest
into a saucepan, add
125mlj4fl oz water and
cook gently, stirring
frequently until the
sugar has dissolved and
the dates have softened.
Remove from the heat and
add the chocolate. Cool
slightly, then add the
eggs, one at a time,
beating well after each.
Sift together the flour,
bicarbonate of soda and
salt, then add
alternately with 50ml/2fl oz water, beating until smooth. Turn into the prepared tin.
Sprinkle the walnuts
over the surface and
bake for 25 to 30
minutes. Leave to cool in the tin, then cut into bars and serve.