1/2 cup butter
1 cup brown sugar
5 Granny Smith apples — peeled, cored, quartered, and thinly sliced
3 (9 inch) refrigerated pre-rolled pie crusts
1 cup white sugar, divided
2 teaspoons ground cinnamon, divided
1/4 cup white sugar
1 tablespoon butter, cut into small chunks
Preheat oven to 350 degrees F.
Place 1/2 cup butter into a heavy cast iron skillet, and melt butter in the oven. Remove skillet and sprinkle with brown sugar; return to oven to heat while you prepare the apples.
Remove skillet, and place 1 refrigerated pie crust on top of the brown sugar. Top the pie crust with half the sliced apples. Sprinkle apples with 1/2 cup of sugar and 1 teaspoon of cinnamon; place a second pie crust over the apples; top the second crust with the remaining apples, and sprinkle with 1/2 cup sugar and 1 teaspoon cinnamon. Top with the third crust; sprinkle the top crust with 1/4 cup sugar and dot with 1 tablespoon of butter. Cut 4 slits into the top crust for steam.
Bake in the preheated oven until the apples are tender and the crust is golden brown, about 45 minutes. Serve warm.