Put flour and salt into bowl, cut in shortening until particles are the size of small peas. Combine eggs and water, sprinkle over flour mixture. Toss lightly til moistened.
Roll out half of dough to fit 13x9x2 pan. Fill with apples. Combine sugar and cornstarch in saucepan, blend in water. Cook, stirring constantly till thickened. Pour over apples and sprinkle with cinnamon. Roll out remaining dough and place over apples. Seal edges and cut slits for steam.
Bake at 400 degrees F for 10 minutes, then at 350 degrees F for 20-30 minutes, till apples are tender and crust is golden. Frost when cool. To make the icing cream the butter and add the other ingredients. Adjust milk to desired spreading consistency.