Preheat oven to 450°. On a lightly floured surface, roll dough to a 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim crust to 1/2 in. beyond rim of plate; flute edge. Line unpricked pastry with a double thickness of heavy-duty foil. Fill with dried beans, uncooked rice or pie weights., Bake at 8 minutes. Remove foil and weights; bake until lightly browned, 5-7 minutes longer. Cool on a wire rack. Reduce oven temperature to 350°., Meanwhile, in a small bowl, beat confectioners' sugar and peanut butter until crumbly, about 2 minutes. Set aside., In a large heavy saucepan, combine the sugar, cornstarch, flour and salt. Stir in milk until smooth. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer., Remove from the heat. Stir a small amount of hot mixture into egg yolks; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir 2 minutes longer. Remove from the heat. Stir in butter and vanilla., Sprinkle 1 cup peanut butter mixture over crust. Pour hot filling over top., In a large bowl, beat egg whites and cream of tartar on medium speed until soft peaks form. Gradually beat in sugar, 1 tablespoon at a time, on high until stiff glossy peaks form and sugar is dissolved. Spread evenly over hot filling, sealing edges to crust. Sprinkle with remaining peanut butter mixture., Bake until the meringue is golden brown, 12-15 minutes. Cool on a wire rack for 1 hour. Refrigerate for at least 4 hours before serving. Store leftovers in the refrigerator.