Prepare the Crust: In a large bowl, whisk together flour, salt, and sugar. Cut in the frozen butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining.

Add Ice Water: Gradually drizzle in the ice water, one tablespoon at a time, mixing gently with a fork until the dough just begins to come together. Divide the dough in half, form into two flat disks, wrap in plastic, and chill for at least 1 hour.

Make the Filling: In a separate bowl, gently combine the pitted sour cherries, granulated sugar, cornstarch, almond extract, and lemon juice. Set aside while you roll out the dough.

Assemble the Pie: Preheat your oven to 400°F (200°C). On a lightly floured surface, roll one dough disk into a 12-inch circle and carefully place it into a 9-inch pie dish. Pour the cherry mixture evenly into the crust. Roll out the second disk and place it over the filling (or create a lattice top).

Finish and Bake: Crimp the edges to seal. Cut several vents in the top crust or lattice. Whisk the egg and milk for the egg wash and brush lightly over the top crust. Sprinkle sparingly with extra sugar. Place pie on a baking sheet.

Bake for 15 minutes at 400°F (200°C). Then, reduce the oven temperature to 375°F (190°C) and continue baking for 40-45 minutes, or until the crust is golden brown and the filling is bubbling thickly. If the edges brown too quickly, cover them loosely with foil.

Cool Completely: Let the pie cool on a wire rack for at least 4 hours before slicing. This is essential for the filling to set properly.