STEP 1: PREPARE THE APPLE FILLING

Start by preparing the apple filling. In a large mixing bowl, combine the diced apples, lemon juice, granulated sugar, ground cinnamon, nutmeg, and cornstarch. Toss until the apples are evenly coated. Let this mixture sit for about 10-15 minutes. This allows the flavors to meld and the apples to release some of their juices.

STEP 2: MAKE THE COOKIE DOUGH

While the apples are resting, you can make the cookie dough. In a separate large bowl, cream together the softened butter, granulated sugar, brown sugar, and salt until light and fluffy. This process typically takes about 2-3 minutes.

Next, add the egg and vanilla extract to the butter mixture. Mix until well combined. Gradually add the all-purpose flour, mixing until just combined. Be careful not to overmix; this will help ensure your cookies remain tender.

STEP 3: CHILL THE DOUGH

Once the dough is mixed, cover it with plastic wrap and refrigerate for about 30 minutes. Chilling the dough makes it easier to handle and helps the cookies maintain their shape while baking.

STEP 4: PREHEAT THE OVEN

Preheat your oven to 375°F (190°C). This ensures that your cookies bake evenly and develop a beautiful golden color.

STEP 5: ASSEMBLE THE COOKIES

After the dough has chilled, remove it from the refrigerator. Roll out a portion of the dough on a floured surface to about ¼-inch thickness. Using a round cookie cutter or a glass, cut out circles of dough. Aim for about 3 inches in diameter.

Once you have your circles, place a tablespoon of the apple filling in the center of half of the circles, leaving a little space around the edges. Top each filled circle with another dough circle, pressing the edges together to seal. You can use a fork to crimp the edges for a decorative touch and to ensure the filling stays inside.

STEP 6: APPLY EGG WASH

In a small bowl, whisk together the egg and milk to create an egg wash. Brush the tops of the cookies with the egg wash, which will give them a beautiful golden color as they bake. If desired, sprinkle a bit of extra sugar on top for added sweetness and crunch.

STEP 7: BAKE

Place the assembled cookies on a baking sheet lined with parchment paper. Bake in the preheated oven for about 15-20 minutes, or until the cookies are golden brown and slightly puffed. Keep an eye on them to avoid over-baking.

STEP 8: COOL AND SERVE

Once baked, remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely. Enjoy your apple pie cookies warm or at room temperature. They can be served plain or drizzled with icing for an extra special treat!