In 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.

In medium mixing bowl, beat egg whites until stiff.

Beat in cream of tarter, white sugar, and 1 teaspoon vanilla.

Spread meringue over pie filling.

Bake at 375 degree F (190 degrees C) until meringue peaks turn a golden brown.