In a large mixing bowl, combine the all-purpose flour, salt, and sugar.

Add the cold butter cubes to the flour mixture. Use a pastry cutter or your hands to work the butter into the flour until the mixture resembles coarse crumbs.

Gradually add ice water, one tablespoon at a time, and mix gently after each addition. Stop adding water when the dough starts to come together.

Gather the dough and divide it into two equal portions. Flatten each portion into a disc, wrap them in plastic wrap, and refrigerate for at least 1 hour.

In a mixing bowl, combine the diced apples, granulated sugar, cinnamon, nutmeg, salt, lemon juice, and cornstarch. Toss until the apples are evenly coated. Let the mixture sit for about 15 minutes to allow the flavors to meld.

Preheat your oven to 375°F (190°C).

Roll out one disc of chilled pie dough on a lightly floured surface to about 1/8 inch thickness.

Use a round cookie cutter (about 3 inches in diameter) to cut out circles from the dough.

Place a spoonful of the prepared apple filling onto the center of each dough circle.

Gently fold the dough over the filling to create a half-moon shape. Press the edges together to seal.

Use a fork to crimp the edges and create a decorative seal.

Place the assembled mini pies on a baking sheet lined with parchment paper.

Optionally, brush the tops of the pies with a beaten egg for a golden finish.

Bake in the preheated oven for about 18-20 minutes, or until the pies are golden brown and the filling is bubbly.

Once baked, remove from the oven and allow the pies to cool slightly before serving.