1In a double boiler, whisk together the brown sugar, flour, and cornstarch. Add just enough milk to make a paste. Mix in beaten egg yolks, and then add the remainder of the milk. Cook slowly, stirring constantly; when thick, remove from heat. Add butter or margarine and 1 teaspoon vanilla. Pour the filling into the baked pie shell.
2In medium mixing bowl, beat egg whites until stiff. Beat in cream of tarter, white sugar, and 1 teaspoon vanilla. Spread meringue over pie filling.
3Bake at 375 degree F (190 degrees C) until meringue peaks turn a golden brown.