In a large mixing bowl, whisk together all-purpose flour, granulated sugar, and salt until evenly combined. Cut in cold unsalted butter until it resembles coarse crumbs, about 5 minutes. In a separate bowl, whisk together large egg, ice water, and lemon juice. Pour this mixture into the flour and butter blend, stirring gently until just combined into a soft dough.

Divide the dough into two pieces, wrap in plastic wrap, and refrigerate for at least 30 minutes.

Peel, core, and slice chosen apples. Toss the sliced apples with cornstarch, sugar, ground cinnamon, nutmeg, vanilla extract, and lemon juice until evenly coated.

Preheat your oven to 375°F (190°C) and prepare a 9x13-inch baking pan by lightly greasing it.

Roll out the larger dough piece into a rectangle that fits in the bottom of your baking pan. Aim for about 1/8-inch thickness and transfer into the pan.

Spoon the apple filling over the rolled-out dough evenly, spreading it to ensure every slice is packed with flavor.

Roll out the second piece of dough and place it over the filling, crimping the edges to seal. Cut small vents in the top crust.

Bake for 45-50 minutes, or until the crust is golden brown and the filling is bubbling.

Remove from the oven and let cool for at least 15 minutes before preparing the glaze.

Whisk together powdered sugar, melted butter, and milk until smooth. Spread the glaze over the cooled apple slices.