Preheat the oven to 400 degrees Fahrenheit.
Cover the bottom of a pie pan with pie pastry.
Peel, core and slice the Granny Smith apples.
In a large bowl combine the sugar, flour, salt, cinnamon, nutmeg, allspice and apples.
Pour the mixture into the pastry lined pie pan.
Dot the apples with the butter and then cover the pie with a top pastry.
Seal the edges and cut steam vents. Brush the pie with egg whites to allow the crust to brown nicely (This is optional, but provides a nice looking pie).
Bake for 40 minutes or until crust is golden browned.
Remove from the oven and allow the pie to completely cool.
Making the Glaze
In a small bowl combine the softened butter, powdered sugar and vanilla. Then slowly mix in the milk, 1 tsp at a time until the glaze has a runny texture. Mine took 5 tsp of milk.
Pour the glaze over the pie and allow to set. Approximately 15 minutes.
Slice and eat.