In a small bowl, mix together 1/2 cup sugar and cornstarch. Place egg yolks in a separate bowl and slowly whisk in scalded milk. Whisk in sugar mixture, then pour this mixture into top of a double boiler. Cook, stirring constantly, until mixture coats the back of a spoon. Remove from heat.
Place 1 cup of hot custard mixture in a small bowl and stir in chocolate chips until mixture is smooth and chocolate is melted. Pour into bottom of baked pastry shell and chill in refrigerator.
Soften gelatin in cold water for 5 minutes, then stir into remaining custard mixture. Chill until mixture is slightly thickened. In a medium glass or metal bowl, beat egg whites until foamy. Continue to beat while slowly adding 1/2 cup sugar, until whites form stiff peaks. Fold whites into custard mixture. Gently pour this mixture over chocolate layer in pastry shell. Chill until completely set, at least 4 hours.
Just prior to serving, whip 1 cup cream until stiff. Garnish pie with whipped cream and chocolate curls if desired.