Stir together cookie crumbs and 1/4 cup melted butter; press firmly into a greased 9" deep-dish pieplate. Bake at 350º for 8 minutes. Remove crust from oven, and sprinkle chocolate morsels into warm crust. Let stand 5 minutes or until morsels melt; carefully spread chocolate over bottom of crust with a spatula. Set aside.
Stir together whipping cream and next 3 ingredients in top of a double boiler; bring water just to a simmer. Cook over simmering water 6 to 8 minutes or until thoroughly heated.
Meanwhile, sprinkle gelatin over cold water in a small bowl; let stand 1 minute.
Gradually whisk one-fourth of warm cream mixture into egg yolks. Add to remaining warm cream, whisking constantly. Whisk in softened gelatin. Cook over simmering water 3 to 5 minutes or until custard reaches 160°. Remove from heat; add 1 tablespoon butter, stirring gently until butter melts. Cool filling to room temperature.
Pour filling into prepared crust. Gently cover with plastic wrap, pressing directly on surface of filling. Chill pie at least 4 hours or until firm.
Sprinkle nutmeg and powdered sugar over pie before serving. Serve with dollops of whipped cream and more nutmeg, if desired. Store pie in refrigerator.
Note: The chocolate layer will harden as the pie chills in the refrigerator. Use a sharp knife and gentle pressure to slice pie.