Preheat oven to 400F°. Grease a 12x17 jelly roll pan.
In a large bowl combine all of the ingredients for the crust. Using a pastry cutter or a fork work everything together (like you would a pie crust). Once everything is combined divide the dough in half. Using your fingers press 1/2 of the dough into the prepared pan. It will be thin, that is ok. Sprinkle the corn flakes evenly over the crust.
In a separate bowl toss the apples, sugar and cinnamon together. Once well coated, spread the apples evenly over the crust. Cover with the remaining crust. It can be a little sticky, so I roll out small portions and place it on top. Kind of like patchwork :)
Bake for 10 minutes a 400F°. Turn down the oven to 350F° and bake for 40 more minutes. Remove from the oven and allow to cool. Once cool you can frost, if using (which you really should).