Preheat your oven to 400°F. Spray your 10 x 15 x 1 pan with non-stick spray.

In a medium bowl, combine the flour, Crisco, sugar, and salt.

In a small bowl, whisk together the egg yolk and milk. Pour into the flour mixture and stir until a cohesive dough forms.

Divide the dough, keeping a little more than half for the bottom crust.

On a floured surface, roll out the larger half of the dough to fit your prepared pan.

Sprinkle the cornflake crumbs evenly over the bottom crust layer.

Prepare the apples by peeling, coring, and slicing them. Toss with sugar and cinnamon.

Layer the cinnamon-sugar apples over the cornflake crumbs evenly.

Roll out the remaining dough and lay it over the apple filling, making slits to allow steam to escape.

Bake in the preheated oven for 30 minutes until the crust is golden browned and filling is bubbling.

Remove from the oven and let it cool for 15 minutes.

Whisk together the powdered sugar, vanilla, and enough milk for icing consistency. Drizzle over warm pie before serving.