Make the crust. Coat a 9-inch pie pan with 2 tsp of the butter. In a food processor, chop the chocolate wafers into fine crumbs. Transfer to a small bowl and mix in the rest of the melted butter. Pat the mixture over the bottom and sides of the pan. Chill for at least 30 minutes.
Set a rack in the middle of the oven and preheat to 350°F Bake the crust for 8 to 10 minutes, until set and dry. Set aside to cool.
Make the filling. Finely chop the chocolate and put it in a medium bowl. In a small saucepan, over medium heat, bring 1/2 cup of the cream to a simmer. Pour it over the chocolate and stir with a whisk until smooth and blended. Stir in the remaining 1/2 cup of cream and refrigerate for 30 minutes, until completely chilled.
In a small bowl, soften the gelatin by stirring it into the milk.
Combine the yolks, eggs, and sugar in a medium bowl and place over slowly boiling water. Whisk until very hot but not scrambled. Remove from the heat and continue to whisk until the mixture is thick and double its size, about 2 minutes. Whisk in the creme de menthe.
Set the bowl of gelatin over simmering water until it has dissolved, about 1 minute, then whisk it into the egg mixture. Set aside to cool.
Whip the white chocolate until just thickened, then fold it into the eggs. Scrape the filling into the pie crust and refrigerate overnight (or at least 2 hours).
Garnish with something dark chocolate, curls, sprinkles, etc.