• If your puff pastry is not already thawed, pull it from the freezer and allow it to thaw at room temperature per the box instructions. Usually, it takes around 30-40 minutes.

Apple Filling

• Into a medium-sized mixing bowl, toss together the diced apples, lemon juice, brown sugar, cinnamon, and salt.
• Sprinkle the flour over the apple mix. Then, break the butter up into little pieces and sprinkle it over the mixture as well.
• Now, using your hands, mix everything until no visible flour and butter are showing, and it's created a slightly creamy look on the apples. Set this in the refrigerator while you roll out the puff pastry dough.

How to Assemble and Bake the Apple Turnovers

• Preheat the oven to 400 degrees Fahrenheit.
• For the puff pastry dough, heavily flour the counter. Unfold the piece of dough and heavily flour the top of it. Roll it into a 12-inch by 12-inch square, which is just slightly bigger than its original size.
• Cut the sheet in half vertically and in half horizontally, giving you four squares.
• To fill the puff pastry squares, I find it most comfortable to turn them, so one of its corners is facing me. Then, evenly distribute the apple filling amongst them all. Lay the filling horizontally in the center but slightly closer to you. Leave about an inch around the pastry's outer edges closest to you clean and lightly wet them with water.
• Fold the opposite side of the dough that is empty over the apple filling, bringing the opposite corner onto the corner closest to you, giving you a triangular shape. Press the outer edges of dough together as best and as tight as you can. Trim off the very outer edges if you'd like to make them look a bit neater. Cut a 1-inch slit on the top of each turnover to allow steam to release while they bake.
• Using a bench scraper, gently lift the turnovers and place them onto a large parchment paper-lined sheet pan, at least an inch apart from each other. Place the pan on the middle oven rack and bake for 15 minutes, rotating the pan halfway through.
• Allow cooling before icing.

Icing

• Stir together all of the ingredients until super smooth.
• To glaze the turnovers, use an eating spoon to distribute and drizzle the icing over the top of each one evenly. As long as the turnovers are cooled down, the icing will set within a few minutes or so.