Combine powdered sugar and peanut butter. Blend until the appearance of biscuit mix. Spread half of this mixture on pie shell. Combine cornstarch, sugar, and salt; add scalded milk and mix well. Pour small amount over beaten egg yolks, mix well; then return to milk mixture. Cook in top of double boiler until mixture thickens. Add butter and vanilla; then pour into prepared pie shell. Top with meringue made form 3 beaten egg whites and 3 tablespoon sugar. Sprinkle remainder of peanut butter mix over neringue. Bake 325 degrees until meringue is brown.