Preheat oven to 375°F.
Place one pie shell on a baking sheet and set aside - this is your bottom crust. Using a small knife, gently pry the second pie crust from the foil pan and place on a lightly floured work surface. Using a lightly floured rolling pin, gently roll the crust to about 11”(28 cm) in diameter. Cut a small circle in the center of the pastry and set aside.
Toss the apple slices with brown sugar, flour, and cinnamon. Add the apple mixture to the bottom crust. Carefully place the rolled out pastry over the top of the apple mixture and bottom crust.
Roll and crimp the edges of the dough together, tightly sealing them.
Bake for an hour or so, until the crust is golden, the juices are bubbling and the apples are soft.