Start by preheating the oven to 400°F. Line two baking sheets with parchment paper. This will help the turnovers bake evenly and keep them from sticking to the pan.

In a small saucepan, mix the diced Granny Smith apples with butter, brown sugar, cinnamon, and salt. Cook over medium-low heat for about 5-10 minutes, until the apples soften and release their juices. Stir occasionally so they don’t stick to the pan. Once the apples are tender, remove the pan from the heat and let the filling cool slightly.

While the filling cools, lay the thawed puff pastry sheets flat on your work surface. Cut each sheet into four squares. You’ll have a total of 8 squares for the turnovers. Be sure to cut evenly so each turnover will cook the same.

Scoop a spoonful of the apple filling into the center of each puff pastry square, making sure to drain any excess liquid to avoid soggy pastry. Don’t overfill the pastry, as it’ll be harder to seal.

In a small bowl, whisk together the egg and water to make an egg wash. Brush the edges of each pastry square with the egg wash. This will help seal the turnover when folded. Fold each pastry over diagonally to form a triangle. Press the edges together, then use a fork to gently press down all the way around the edge, sealing it well.

Use a sharp knife to make small slits on top of each turnover. This will allow the steam to escape while they bake, helping them puff up. Brush the tops of each turnover with the remaining egg wash for a golden finish.

Place the turnovers on the prepared baking sheets and bake for 20-22 minutes, or until they’re golden brown and puffed up. Keep an eye on them toward the end of the baking time to make sure they don’t burn. Once they’re done, remove them from the oven and let them cool for a bit.

While the turnovers cool, mix the powdered sugar and heavy cream in a small bowl. Whisk it together until smooth and creamy. The glaze should be thick enough to drizzle but not too runny.

Drizzle the glaze over each turnover. You can pour a little or a lot, depending on how sweet you like them. Once glazed, they’re ready to serve and enjoy.