Mix all the ingredients well. Grease a 9 x 9 or 8 x 9 or 11 x 7 inch square pan. Pat the mixture into the bottom. Prick with a fork. Bake at 350 deg. F for 15 minutes.
Filling
Combine eggs, sugar, juice and rind. Mix well and pour over the top of the baked base. Return to the oven for 25 minutes.
When cool, dust with icing sugar and cut into squares.