Plate pies were popular in the 70's with people cooking in the enamel plates now reserved for camping trips. This recipe is the basic crust that can be filled with any sort of filling including leftover stew, casserole or even pasta sauce.
In a large bowl rub the butter into the flour and salt until the mixture resembles coarse crumbs and there are no chunks of butter.
Add the egg and just enough water to make a smooth dough. Divide into 2 balls.
Grease the plate with butter. Roll each ball flat just large enough to cover the plate. Place the first in the plate and gently shape to the form of the plate. Fill with the desired leftovers then top with the second sheet of dough.
Using a fork press down the edges of the pie crust so they join. Using a butter knife run it around the edge of the plate to cut off any excess pastry.
Brush the top of the pie with milk then place in an oven preheated to 200 degrees C. As the filling is already cooked you just need to cook as long as it takes to brown the crust and heat the pie filling. (You can add the pie filling hot which reduces the cook time).