In a food processor, combine flour, sugar, and salt. Pulse to combine. Add the butter and pulse a few times just to break the pieces down a bit.

While pulsing, drizzle in 4 tablespoons of ice water. Pulse until dough starts to clump together. Turn out dough onto a lightly floured surface and knead together to form a ball. Shape into a disk and tightly wrap in plastic wrap. Chill for at least 2 hours or up to 3 days.

Preheat the oven to 205°C. Line a baking sheet with parchment paper or a silicone baking mat.

FOR THE FILLING: Peel, core, and slice the apples into 3mm thick slices. Place in a large bowl. Toss with lemon juice until well coated.

Sprinkle apples with sugar and cinnamon and toss until combined. Let the filling steep for 30 min, then bind liquid with corn starch.

On a lightly floured surface, roll pie dough into roughly a 30cm circle. Transfer to the lined baking sheet (the dough will likely hang over the edges.) Arrange the apple filling in the center of the dough, leaving a 7.5cm border.

if you want to freeze it, then now is the moment (adds 20 to 30 min to the baking time.Fold the edges of the dough over the filling towards the center. (The dough will not fully cover the filling).

Pour the butter in, Brush the dough with egg and sprinkle with sugar.

Bake for 45 minutes or until crust is golden brown and filling is bubbly. Let cool on a wire rack for at least 30 minutes before slicing.