Prepare the Dough:
In a large bowl, mix flour and salt.
Cut in the cold butter until the mixture resembles coarse crumbs.
Add the egg and cold water, then mix until a dough forms.
Wrap in plastic wrap and chill for 30 minutes.
Prepare the Apple Filling:
In a bowl, combine sliced apples, sugar, cinnamon, lemon juice, and vanilla extract.
Let the mixture sit for 10 minutes to release flavors.
Roll Out the Dough:
Preheat oven to 375°F (190°C).
Roll out half the dough on a floured surface to fit your baking sheet.
Place the dough on the sheet and spread the apple filling evenly, leaving a small border.
Assemble the Empanada:
Roll out the second half of the dough and cover the filling.
Press the edges together and crimp with a fork to seal.
Brush with beaten egg wash and sprinkle with sugar if desired.
Bake:
Bake at 375°F (190°C) for 30-35 minutes, until golden brown.
Let it cool for 10 minutes before slicing.