Preheat oven to 450°.
Fit dough into a 9-inch pie plate. Fold edges of dough under, and flute. Pierce bottom and sides of dough with a fork. Bake at 450° for 10 minutes or until lightly browned. Reduce oven temperature to 350°.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, milk, and next 3 ingredients in a saucepan, stirring until smooth. Bring to a boil over medium heat. Reduce heat, and simmer, stirring constantly, 5 minutes.
Gradually stir about one-fourth of milk mixture into beaten egg, stirring constantly with a whisk; add to remaining milk mixture. Cook 3 minute. Pour into prepared crust; cover with plastic wrap.
Place egg whites, cornstarch, and cream of tartar in a large bowl. Beat at high speed until foamy. Gradually add 1/3 cup sugar, 1 tablespoon at a time, beating until stiff peaks form.
Remove plastic wrap from filling; spread meringue evenly over filling, sealing to edge of crust. Bake at 350° for 25 minutes; cool on a wire rack 1 hour. Chill 3 hours or until set.