Make the Pie Crust – In a large bowl, whisk flour, salt, and sugar. Add cold butter and cut in with a pastry cutter until pea-sized crumbs form. Slowly add ice water, 1 tablespoon at a time, mixing until the dough comes together. Divide into two discs, wrap in plastic, and chill for at least 1 hour.
Prepare the Apple Filling – In a large bowl, mix sliced apples, sugars, flour, lemon juice, cinnamon, nutmeg, allspice, and vanilla. Let sit for 15 minutes to draw out the juices.
Assemble the Pie – Preheat oven to 400°F (200°C). Roll out one dough disc and fit it into a 9-inch pie dish. Fill with the apple mixture. Roll out the second disc and cut into strips to create a lattice top. Whisk the egg and milk together, brush over the crust, and sprinkle with sugar.
Bake the Pie – Bake at 400°F for 20 minutes. Reduce heat to 375°F (190°C) and continue baking for 30–35 minutes, until the crust is golden brown and the filling is bubbling. Cool for at least 2 hours before slicing.
Serve & Enjoy – Top each slice with a scoop of vanilla ice cream and a light dusting of cinnamon. Serve warm and enjoy the cozy goodness!