Preheat your oven to 400 degrees.
For the cream filling:
In a medium saucepan over medium heat, combine ½ cup sugar, ½ milk, ½ cup heavy cream, & 4 tablespoons of butter. Cook, stirring occasionally, until the butter is melted. Whisk together 2 tablespoons cornstarch, 2 tablespoons milk, & 1 teaspoon vanilla extract. Pour the cornstarch mixture into the milk/sugar mixture. Stir continuously until the mixture is thickened.. Once thickened, remove from the heat and set aside to cool slightly.
For the cinnamon roll crust:
Take one of the 2 pie pastries, and lay it on a piece of parchment paper or a piece of aluminum foil sprayed lightly with non-stick cooking spray. Roll it out slightly. Spread 2-3 tablespoons of softened butter all over the top; sprinkle with ¼ cup sugar and 1-2 tablespoons of cinnamon. Roll the pie pastry up lengthwise; squeeze the pie pastry roll with your hands to tighten up the insides. Slice it into thin cinnamon rolls & then lightly flatten each mini cinnamon roll with the palm of your hand.
For the apple filling:
Combine 4-5 peeled & thinly sliced apples with 1 tablespoon of flour. Set aside.
Assemble the pie:
Lay out the remaining pie pastry into the bottom of a lightly greased pie pan. Spread the cream filling into the bottom of the pastry. Top with the floured apple mixture. Sprinkle on a little sugar, cinnamon, & a couple pats of butter if desired. Place the slightly flattened cinnamon rolls on top of the apples, covering the surface of the pie with them. Brush the beaten egg on top of the cinnamon roll crust.
Bake at 400 degrees for 35-40 minutes, or until the cinnamon roll crust is nicely browned. Cool on a wire rack for 45 minutes. Whisk together the icing ingredients - confectioners sugar, milk, vanilla extract, & softened butter. Drizzle on top of the cooled pie. Let the pie cool for an additional hour or so, or until the pie is completely cooled before slicing & serving.