Preheat the oven to 180 C. Grease and line an 8” cake tin.
Beat together the butter, flour, milk, sugar, eggs and the lemon zest (reserve the juice for the drizzle) until smooth and creamy. Pour cake mixture into prepared tin.
Bake in the preheated oven for 40 to 50 minutes.
Heat the lemon juice in the microwave for 45 seconds, and stir in the icing sugar. While still hot in the tin, pour the lemon juice mixture over cake. (Alternatively, if it is poured over cool cake it gives a glaze to the top)