Mary Berry's Iced Lemon Traybake

225 g (8oz) softened butter
225 g (8oz) caster sugar
275 g (10oz) self-raising flour
1/2 tsp baking powder
4 large eggs
1/2 C milk
grated rind of 2 lemons

FOR THE ICING
3 T lemon juice
225 g (8oz) sifted icing sugar

SELF RAISING FLOUR
12 oz all purpose flour
11/2 T (.65 oz) baking powder
3/4 tsp (.15) salt

Pre-heat oven to 356F. Grease 9 x 13" glass pan or roasting tin then line base with baking parchment or spray with non-stick spray.

Measure all the cake ingredients into a large bowl and beat until well blended. Turn the mixture into the prepared tin and level the top.

Bake in the pre-heated oven for about 35-40 minutes or until the cake has shrunk from the sides of the pan and springs back when pressed in the centre with your fingertips. Leave to cool in the tin.

Mix together the lemon juice and icing sugar to give a runny consistency. Spread out evenly over the cake and leave to set before cutting into 21 pieces.