Grate the frozen butter on top of the flour mixture, and toss until the butter is evenly distributed.
Stir in 4 tablespoons of the ice water. Then add additional ice water, 1 tablespoon at a time, stirring until the dough starts to clump together.
Divide and shape the pie dough into two discs, wrap, and chill in the refrigerator. While pastry is chilling, prepare the filling.
Preheat your oven according to your recipe.
Remove the chilled pie pastry from the refrigerator.
On a lightly floured surface, flatten one ball of dough with your hands. Using a rolling pin, roll the dough to fit your pie plate, about 12-inches in diameter.
Place the pastry into the pie plate carefully without stretching the dough. Add the filling, and brush around the outer edge of the pastry with water or the beaten egg.
Roll out the top pastry and place on top of the filling. Fold the top crust under the bottom crust and pinch or flute the edges.
Glaze by brushing with the beaten egg if desired. If you prefer a shiny crust, brush with milk. If you want a sugary crust, brush with egg and sprinkle with granulated sugar. Cut vent holes.
Following your pie recipe, bake in a preheated oven until the pastry is golden brown.
Remove the pie from oven and let it cool at least 30 minutes before serving.