In a small saucepan, cook evaporated milk, butter, chocolate and sugar over low heat, stirring constantly, until thick as cooked pudding (before it cools). Cool completely. Spoon ice cream into pie crust and spread into an even layer. Spread chocolate mixture over ice cream. Place pie in freezer. Beat heavy cream with electric mixer until soft peaks form. With mixer running, add coffee liqueur and beat until completely mixed. Spread mixture over pie. Cover pie and freeze for at least 4 hours. About fifteen minutes before serving, remove lid and sprinkle with nuts. Place in refrigerator until ready to serve. Serves 8 with each serving = 434 cal, 5 g pro, 42 g carbs, 28 g fat, 43 mg chol, 215 mg sodium.