Generously grease a 30 x 23 cm/12 x 9 inch shallow baking tin. Put the
butter, two-thirds of the icing sugar and the
vanilla extract into a bowl and cream until light
and fluffy.
Sift the flour and fold into the creamed
mixture, a little at a time, until completely
incorporated.
Spread the mixture evenly in the
prepared tin and bake in a preheated oven, 190°C
(375°F), Gas Mark 5, for 20 minutes.
Meanwhile, put
the eggs, granulated sugar, lemon rind and lemon
juice into a bowl. Stir to blend the ingredients but
do not beat together.
Pour the mixture over the
baked pastry layer. Return the tin to the
oven and bake for about 20 minutes until the
topping is set and lightly browned.
Remove the tin from the oven and sift the remaining
icing sugar over the warm cake to cover it
generously. Cut the cake into slices. Remove from
the tin when cool.