1Prepare your favorite pastry crust in a 9 1/2 inch pie plate. Bake according to your directions and then let it cool while you make your custard filling.
2Custard-In a large saucepan, combine sugar, cornstarch, and salt. Gradually stir in milk until smooth. Bring to a boil over medium heat until slightly thickened, stirring constantly.
3Quickly stir 1/3 cup hot mixture into beaten egg yolks. Return this mixture to saucepan. Cook and stir 2 minutes. Remove from heat. Stir in butter and vanilla extract.
4Spread evenly into shell. Set aside. Meringue-Preheat the oven to 375F. Using an electric mixer, beat egg whites until foamy. Gradually add salt, cream of tartar, sugar, and vanilla extract, beating until stiff and shiny.
5Quickly spread over filling to the edge. Bake 15 minutes or until golden brown. Remove from oven; cool in refrigerator for 2 hours to set properly before serving.