Preheat the oven to 375 degrees F (190 degrees C).
In a large bowl, combine flour and salt. Cut in the butter until the mixture resembles coarse crumbs. In a cup, beat egg yolk, stir the cold water into the yolk. Gradually stir the egg mixture into the flour mixture until dough can be packed into a ball. On a clean dry surface, roll out 1/2 of the dough large enough to cover the bottom and sides of a 9x13 inch pan. Lay the dough in the pan.
Place the cornflakes over the dough in the pan. Arrange apple slices over the top of the corn flake layer. Sprinkle the sugar and cinnamon over the apples. Roll out the second half of the dough to cover the entire pan. Lay over the filling and pinch the edges of the two crusts together. Beat the egg white until foamy, and brush onto the top crust.
Bake for 45 to 50 minutes in the preheated oven, until golden brown. Drizzle with glaze while still warm.
To make the glaze: In a small bowl, beat the confectioners' sugar with the milk and almond extract until smooth.