Preheat oven at 325F.
Mix together for crust: margarine, flour and icing sugar and pat into 9 x 13 pan and bake for 15 minutes.
In a bowl add baking powder, flour and sugar. Add to slightly beaten eggs. Add lemon juice and lemon rind. Mix well.
Pour over the crust and return to oven for 35-40 minutes at 325F. Sprinkle top with icing sugar after cake is cooked and cooled slightly.