In a bowl, stir together the wafer crumbs, sugar, and butter until the mixture is combined well. Pat mixture onto bottom and sides of a buttered 9-inch pie plate. Bake in the middle of a preheated 450f oven for 5 minutes. Let cool completely. In a metal bowl, sprinkle the gelatin over 1/3 cup of the cream and let it soften for 5 minutes. Whisk in the sugar, creme de menthe, creme de cacao, and the egg yolks. Set the bowl over a saucepan of simmering water, and cook the mixture, whisking constantly, until it measures 160f on a candy thermometer. Transfer the custard to an ice water bath and stir until it is cooled and thickened. In another bowl, beat the remaining cream until it holds stiff peaks. Fold it into the custard thoroughly. Pour the filling into the crust and chill the pie for at least 4 hours or until it is set. Sprinkle with grated chocolate and serve.