One hour before you plan on using the pie crusts, measure out the olive oil and pour into a small plastic container and place in the freezer until solid, 1 hour. About 30 minutes after the oil goes into the freezer, preheat your oven to 180° C (350° F).
In a mixing bowl, add the flour and salt and whisk together. In a measuring cup, add the milk and the oil from the freezer (the oil will chill the milk).
Add the milk and oil all at once to the flour then cut mix with a large sturdy fork or pastry cutter until well mixed to form a shaggy ball, if the ball is not forming, add a tablespoon of cold water and mix in until you get the right consistency. Divide mixture in half and shape each half into a thick flat disk.
Wrap each with plastic wrap and place in the fridge to chill for at least 15 minutes. Don't have plastic wrap, just put each half in a zip lock bag and pat down to a disk shape.
Lightly flour your work surface, unwrap a disk of dough and roll out to desired thickness, place in your pie dish.
Add prepared fillings of your choice.
Roll out the second disk of dough and place on top of the pie, or you can cut strips to make a lattice, or cut shapes to place on top of the pie. Flute the edge as desired.
Brush the top crust with the beaten egg, and sprinkle with some sugar for fruit pies.
Bake until the crust is golden brown. Remove from oven and allow to cool for 30 minutes or more.
Slice, serve, and enjoy.