1Heat oven to 400°F. In medium bowl, mix all crust ingredients until soft dough forms. Press firmly and evenly against bottom and side of ungreased 9-inch glass pie plate. Bake 12 to 15 minutes or until light brown. Cool completely on cooling rack, about 30 minutes.
2In 3-quart saucepan, heat milk and marshmallows over low heat, stirring constantly, just until marshmallows are melted. Refrigerate about 20 minutes, stirring occasionally, until mixture mounds slightly when dropped from a spoon. (If mixture becomes too thick, place saucepan in bowl of warm water; stir mixture until proper consistency.) Gradually stir in liqueur.
3In chilled medium bowl, beat whipping cream with electric mixer on high speed until stiff. Fold marshmallow mixture into whipped cream. Spread in pie crust. Sprinkle with grated chocolate. Cover; refrigerate until set, at least 4 hours but no longer than 48 hours. Store in refrigerator.