Mother's Chocolate Pie

3/4 cup sugar
5 tablespoons baking cocoa
3 tablespoons cornstarch
1/4 teaspoon salt
2 cups milk
3 egg yolks, beaten
1 teaspoon vanilla extract
1 pie crust baked
MERINGUE:
3 egg whites
1/4 teaspoon cream of tartar
6 tablespoons sugar

In a saucepan, mix sugar, cocoa, cornstarch and salt; gradually add milk. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes more. Remove from heat. Stir about 1 cup of the hot filling into the egg yolks. Return to saucepan and bring to a gentle boil. Cook and stir 2 minutes. Remove from the heat and stir in vanilla. Pour hot filling into pie crust. For meringue, immediately beat egg whites with cream of tartar until soft peaks form. Gradually add sugar and continue to beat until stiff and glossy. Spread evenly over hot filling, sealing meringue to pie crust. Bake at 350° for 12-15 minutes or until golden.