Mix crushed cookies with butter and press into a 9 inch pie pan. Chill. Stir chocolate ice cream to soften and blend in 1/4 cup coffee liqueur. Spoon into pie shell. Sprinkle with crushed Heath Bars and place in freezer 1 hour. Soften vanilla ice cream and add 1/4 cup coffee liqueur. Spoon over the chocolate mixture. Freeze overnight. Garnish by piping whipped cream around the pie. Cut into wedges and serve with a drizzle of coffee liqueur over the top.