In a medium bowl, mix together the crushed cookies and melted butter. Press the crumb mixture into a 9 inch pan and bake for 10 minutes. Cool.

In a small dish, dissolve gelatin in cold water. Set aside. In a medium saucepan, scald milk and add in 1/2 cup sugar.

Separately mix cornstarch with salt and beaten egg yolks and add into milk mixture. Cook in the top of double boiler, stirring constantly, until mixture thickens. Stir in gelatin. Divide this custard in half.

Melt chocolate, stir in vanilla, and mix with half the custard. Pour into the baked pie shell. Tip pan around so chocolate coats all sides. Cool remaining half of custard.

Beat egg whites with cream of tartar, adding in sugar a little at a time, until stiff. Fold into remaining custard. Stir in rum. Spread over chocolate layer. Chill well, overnight if possible.