Bake the empty pie shell according to directions.
In a small bowl, place the confectioner's sugar and peanut butter. Cut sugar into peanut butter with a fork until the mixture is crumbly. Place half of the peanut butter mixture in the bottom of the baked pie shell and reserve the remainder.
In a large saucepot, place the egg yolks, milk, 2/3 cup sugar, vanilla, salt, and cornstarch. Cook over medium to medium-low heat until thick, stirring constantly. Pour over peanut butter in pie crust.
Beat 4 egg whites until foamy and then add sugar. Continue beating until soft peaks form. Spread over the top of the pie, being careful to seal it at the edges. Sprinkle the remainder of the peanut butter crumble over the top of the pie. Bake peanut butter pie at 325 for 30 minutes.
Refrigerate for several hours before serving. (Or serve warm - my favorite!)
