1In the top of a double boiler, combine brown sugar, cornstarch, and 1/4 teaspoon. salt. Stir in milk and corn syrup. Cook over boiling water, stirring constantly, 20 minutes or until thickened.
2In a medium bowl, beat egg yolks until thick and lemon colored. Gradually stir 1/2 cup of hot mixture into yolks. Pour back into remaining milk mixture, stirring constantly. Cook 5 minutes over boiling water, stirring frequently. Remove from heat; stir in butter, vanilla and 3/4 cup pecans. Pour into pastry shell. Preheat oven to 350 degrees F (175 degrees C.)
3Beat egg whites cream of tartar, and pinch of salt until foamy. Gradually add sugar, beating until stiff peaks form. Spread meringue over filling, sealing to edge of pastry. Sprinkle with remaining 1/4 cup pecans.
4Bake in the preheated oven for 12 minutes, or until golden brown. Cool to room temperature. Chill thoroughly.