Step 1

In a 10-inch cast iron skillet, melt the butter and brown sugar over medium heat. Stir until the butter is melted and the sugar is dissolved. Remove from the heat and set aside to cool for 5-10 minutes.

Step 2

Preheat the oven to 350°F (175°C).

Step 3

Peel, core, and slice the apples into bite-sized chunks. Toss in a large bowl with the granulated sugar, flour, and cinnamon until well coated.

Step 4

Carefully place one of the pie crusts over the butter-brown sugar mixture in the skillet. Make sure not to press the crust down into the mixture.

Step 5

Pour the coated apples over the pastry and spread evenly. Then, layer the second sheet of pastry on top, covering them completely. Carefully press the edges of the two pastry sheets together to seal the crust. Cut a couple of slits in the top to allow steam to escape.

Step 6

Place the skillet onto a baking sheet to catch any drips and brush the top with the lightly beaten egg. Sprinkle the coarse sugar evenly over the top, if using.

Step 7

Bake for 60-70 minutes, or until the pastry is golden and the caramel is bubbling up the sides.

Step 8

Remove the skillet from the oven and let the pie cool for 15-20 minutes before serving. Enjoy!