Upside-Down Apple Tart

Make a simple rustic apple pie with Granny Smith apples and a few other ingredients you probably already have on hand: flour, butter, and salt.
Freeze 1 cup of sliced butter for 30 minutes. Whisk the cold butter, flour, salt, and 1/4 cup sugar in a food processor 7-8 times or until the mixture resembles coarse flour. Add 1/2 cup ice-cold water and 1 tbsp. l. Beat one at a time until the mixture is combined and a dough forms. Place the dough on a piece of plastic wrap and form a disk. Wrap in plastic wrap and refrigerate for 2 to 24 hours.In a large bowl, gently combine the apples, 1/2 cup butter, and remaining 1 1/2 cups sugar. Transfer the apple mixture to a 10-inch-diameter cast-iron skillet. (The pan will be very fluffy.) Cook over medium-low heat for 1 hour to 1 hour and 15 minutes, or until the liquid is reduced, thickened, and golden brown, stirring only once every 15 minutes. (Depending on your stove, you may need to lower the temperature if the mixture starts to burn from the bottom.)Preheat the oven to 425 degrees. Roll out the dough and place it on a lightly floured surface. Roll out the dough into a 12-inch circle; place on top of the warm apple mixture, pressing the edges against the sides of the pan.Bake at 425 ° C for 25 minutes or until the crust is golden brown and flaky. Let cool for 10 minutes. Run a knife around the edge of the pan; flip the pie onto a cutting board or serving platter.