Mix flour with sugar, baking powder and salt. Cut shortening. Place egg in a 3/4 cup-fill the cup with milk to make 3/4 cup. Add egg and milk mixing lightly. Divide dough into two parts. Roll out to get a 10 1/2 X 15 1/5 inch cookie sheet. Slice enough apples to fill crust. Combine sugar, cinnamon and powdered sugar. Sprinkle over apples. Roll out remaining crust-place over apples; seal edges. Bake 400 degrees for 20 to 30 minutes. Mix powdered sugar and enough milk to make a thin icing. Pour over cake. Cut in squares to serve.
