To make the pie crust, combine flour and sugar in a food processor. Add butter and pulse until crumbly. With processor running, add water one tablespoon at a time until dough comes together and forms a ball. Divide dough into two balls, shape into discs, and wrap with plastic wrap. Chill in refrigerator 30 minutes. On a lightly floured surface, roll one disc of dough into a 15-inch rectangle. Lift dough using a rolling pin and arrange in a 9x15-inch baking sheet.
Stir together filling ingredients until well blended. Spoon filling over the crust. Beat egg and milk with a fork until pale and frothy. Brush egg wash over edges of pie crust.
Remove the second dough from the refrigerator. On a well-floured surface, roll dough into a 15-inch rectangle. Using a pizza cutter, cut dough into uniform strips. Arrange in a lattice pattern over pie filling, pressing edges of dough together to seal. Brush egg wash over lattice crust. Sprinkle crust with raw sugar.
Preheat oven to 350 degrees. Bake 40-45 minutes, or until crust is golden brown and filling is bubbly. Let cool slightly before slicing and serving. Serve with vanilla ice cream, if desired.