Add butter, egg and cold water to the flour mixture. Pulse until mixture resembles coarse crumbs.
Shape the dough into a ball and wrap dough with plastic. Place in the fridge for about 30 minutes to 1 hour.
Roll the dough on a lightly floured work surface into a thin sheet and cut out discs using a large biscuit cutter.
Brush the edges of the empanada discs with the beaten egg to help better seal them.
Fold the empanada discs and seal the edges with a fork or your fingers. Brush the top of the empanadas with the rest of the beaten egg. Chill the empanadas for about 20 minutes.
Pre-heat the oven to 400 F and bake for 12-15 minutes or until golden.