Preheat oven to 400 deg. Unroll pie crust onto a glass pie dish. Brush with melted butter and sprinkle evenly with cinnamon and granulated sugar. Pour the 1/2 cup of Wheaties to cover bottom of pie crust. (This is a key ingredient, trust me no one will know its there but it does the job, keeps the pie together).

Place sliced apples in a mound on top of the Wheaties. In a large bowl, combine butter, flour and brown sugar and form into crumbles using fingers or a pastry blender. Sprinkle crumbles over apples.

Sprinkle granulated sugar evenly over crumbles. Bake pie until the top and crust are a golden brown and the filling is bubbling, about 40 minutes (cover top/crust with foil if necessary to prevent it from getting too dark). Remove from oven and allow to cool completely on a cooling rack.

In a small bowl, whisk together powered sugar, vanilla, cinnamon and milk to form the icing (add more sugar or milk to reach desired consistency). Using a pastry bag or a Ziploc bag with one end cut off, pipe on the icing in a swirl on top of the crumbles on fully cooled pie.