Preheat oven to 400° and line a large baking sheet with parchment. In a medium pot over medium heat, melt butter. Add apples, sugar, cinnamon, salt, and lemon juice. Bring to a simmer and cook until apples are soft and most of the juice has cooked off, about 8 minutes. Let cool.
On a lightly floured surface, roll puff pastry out to a 12” square. Divide into 8 rectangles.
Spoon apples into center of 4 rectangles, leaving a ¼” border around puff pastry. Top with remaining rectangles and crimp edges together with a fork. Using a sharp knife or kitchen shears, cut 4 slits into tops of each pie. Brush with egg wash and sprinkle with cinnamon sugar.
Place pies onto prepared pan and bake until golden, 25 minutes.
Recipe by 5* trending recipes with videos at https://food.theffeed.com/2019/08/28/mcdonalds-apple-pie/