1-First: preheat the oven to 400°F (205°C) and thaw the puff pastry following the package directions. In a skillet, melt 1 tablespoon unsalted butter over medium heat, then add the peeled and diced Granny Smith apples, cooking them for about 5 minutes while stirring occasionally until they soften.

2-Lower the heat to low and mix in 1/4 cup lightly packed light brown sugar, 1/2 teaspoon cinnamon, and 1/8 teaspoon salt. Let it simmer for 3 minutes until the apples are soft and caramelized, then remove from heat and let the mixture cool completely.

3-Assembling and Baking the Turnovers: Roll one sheet of puff pastry into an 11-inch square and cut it into 4 equal squares. Spoon the cooled apple filling onto half of each square, leaving a 1/2-inch border. Beat 1 egg with 1 tablespoon water for the egg wash and brush it lightly on the pastry edges.

4-Fold each square over the filling to form triangles and crimp the edges with a fork to seal them tightly. Repeat with the second sheet to make a total of 8 turnovers. Arrange them on a parchment-lined baking sheet, spacing them at least 1 inch apart, and cut 2-3 small slits on top to let steam escape.

5-Optionally, refrigerate the turnovers uncovered for 20 minutes to help prevent leaking. Brush the tops with the egg wash and bake for 20-23 minutes until they turn golden brown and puff up nicely. Once done, mix 1/2 cup powdered sugar with 1 to 2 tablespoons heavy whipping cream for the glaze and drizzle it over the warm turnovers before serving.