Step 1: Make the Crust: In a large bowl, mix the crust ingredients: 3/4 cups all-purpose flour, 3/4 teaspoon salt, 11/2 cups shortening, and the 1 egg yolk plus enough milk to make 1 cup of liquid. Mix until a cohesive dough forms.
Step 2: Prep Pan and Bottom Crust: Tip: Use a 15×10-inch cookie sheet pan. Roll out half of the dough to fit your cookie sheet pan. Place the dough in the pan.
Step 3: Layer the Filling: Sprinkle the bottom crust with 2-3 handfuls of Corn Flakes. Place the sliced apples on top of the Corn Flakes.
Step 4: Season and Dot: In a small bowl, mix the 1 cup sugar and 1 teaspoon cinnamon and sprinkle the mixture evenly on top of the apples. Dot the filling with 4-8 Tablespoons cubed butter.
Step 5: Add Top Crust: Roll out the remaining half of the dough and place it over the apple filling to cover. Crimp the edges tightly to seal the pie.
Step 6: Egg Wash and Slits: In a small bowl, beat the 1 egg with 1 teaspoon sugar and brush this mixture onto the top crust. Cut a few slits in the top of the pie crust to allow steam to escape.
Step 7: Bake: Bake at 425∘F for 25-30 minutes, or until the crust is golden brown.
Step 8: Frost and Serve: While the pie is still hot, mix the frosting ingredients: 12/3 cup powdered sugar, 2-3 dashes vanilla extract, and enough milk to make a thin frosting.2 Drizzle the thin frosting evenly over the hot pie. Slice and serve warm.