- 5 large apples (combination of Granny Smith or Golden Delicious), peeled, cored and sliced into eighths.
- 1 sheet store-bought puff pastry, thawed
- 1 cup sugar
- 6 tablespoons butter, cut into 1-inch pieces
- juice of half a lemon
- 1 pinch sea salt
- Heat the oven to 375 F. Sprinkle the lemon juice evenly onto the apples to prevent them from discoloring.
- Place sugar in a cast-iron skillet and melt over medium heat, cooking and stirring occasionally until the sugar is a light butterscotch color and its temperature reaches 320 degrees (measure with a candy thermometer). Turn off the heat. The temperature will continue to rise.
- Once the temperature reaches 350 degrees, whisk in the butter, 1 piece at a time. Make sure each piece is incorporated before adding the next, then add the salt.
- Cover the caramel with the apple slices, Turn the heat back on to medium-high and cook for 15 minutes. Stir to make sure the apples are cooking evenly.
- When the apples have cooked and the liquid starts getting bubbly, cover the pan with the puff pastry. Tuck in the edges around the apples and prick the pastry with a fork.
- Bake until the edges are deep amber in color and the pastry is puffed and golden, 40 to 45 minutes. If the pastry gets too dark cover with a piece of foil.
- Remove from the oven and cool for 10 minutes before inverting onto a plate larger than the pan.