Toss apples through salt together in a large bowl until well blended and pile into unbaked pie shell. (If making a two crust pie, omit the next step and crimp a top pastry into place, cut vent holes, brush with egg, sprinkle with sugar and bake as below.)
In a medium bowl, mix the flour, brown sugar, and cinnamon. Cut the butter into the flour mixture with a pastry blender until coarse crumbs form. Stir in the nuts. Crumble on top of fruit.
Bake at 425 F for 15 minutes. Reduce the heat to 350 F and bake until the crust is golden and the fruit is tender, about 40-50 minutes longer. If topping browns too quickly, tent with foil.
Makes one 9-inch pie.
