If making homemade pie crust, prepare the dough for two 9-inch pie shells according to your favorite recipe, ensuring it has time to chill for at least 1 hour before use. Alternatively, use store-bought pie shells and follow package instructions. Place the oven rack in the center position and preheat the oven to 400°F (204°C). I find that chilling the dough really helps achieve a wonderfully flaky crust.

In a large bowl, combine the sliced Granny Smith apples, white sugar, brown sugar, flour, ground cinnamon, ground nutmeg, lemon juice, and lemon zest. Toss everything together until the apples are thoroughly coated in the sugar and spice mixture. Let the filling sit while you prepare the crusts—this helps draw out excess juice from the apples.

Remove the chilled pie crust dough from the fridge and let it rest at room temperature for 5–10 minutes to become more pliable. On a lightly floured surface, roll one disc of dough into a 12-inch circle about 1/8-inch thick. Carefully line the bottom of a deep dish pie plate with the rolled dough. Spoon the apple filling (from Step 2) evenly over the bottom crust, discarding any accumulated juices to avoid a soggy base. Roll out the second disc of dough to a similar thickness and place it over the apple filling.

Trim the excess dough along the edge of the pie plate with a sharp knife. Carefully pinch together the edges of the bottom and top crusts, folding them under themselves for a tidy seal. Rotate the pie plate as you work for best results. Use a sharp knife to cut 4 slits in the top crust to allow steam to escape during baking. Set the prepared pie on a baking sheet to catch any bubbling juices.

Brush the surface of the pie with the beaten egg to help develop a golden, shiny crust. Sprinkle sanding sugar evenly over the top for a sparkly, crunchy finish if desired. To prevent the edges from over-browning, cover them with a pie shield or strips of foil for the initial baking period. Bake at 400°F (204°C) for 25 minutes, then carefully remove the pie shield and reduce the oven temperature to 375°F (190°C). Continue baking for 30–35 minutes, or until the top crust is golden brown and the filling is bubbling. I like to use sanding sugar for an extra festive appearance, but it’s totally optional!

Allow the baked pie to cool on a wire rack at room temperature for at least 3 hours. This patience ensures the juices settle, making the pie easier to slice and helping the flavors develop.