Black Bottom Pie

Stir together ½ c. sugar, cornstarch and salt in saucepan. Blend milk and egg yolks; stir into sugar mixture. Cook over medium heat, stirring constantly, just until mixture boils. Reserve 1 c. of the custard mixture; set aside. Soften gelatin in cold water; stir into remaining hot custard mixture. Stir in rum. Place pan in bowl of ice and water or chill in refrigerator, stirring occasionally, until mixture mounds slightly when dropped from spoon. Combine chocolate and the reserved custard mixture. Pour into baked pie shell. Beat egg whites and cream of tartar until foamy. Beat in 1/3 c. sugar, 1 T. at a time; continue beating until stiff and glossy. Do not overbeat. Fold remaining custard mixture into meringue. Spread on chocolate mixture. Chill at least 3 hours or until set. If desired, garnish with whipped cream; sprinkle with shaved chocolate.