FOR THE CHOCOLATE MINT COOKIE CRUST: In a small bowl stir together crushed cookies and melted butter or margarine till well combined. Press crumb mixture evenly onto the bottom of a greased 9-inch springform pan.
FOR THE FILLING: In a large bowl combine cream cheese, sugar, and cornstarch. Beat with an electric mixer till smooth. Add eggs and egg yolk, one at a time, beating well after each addition. Beat in creme de menthe and vanilla extract. Stir in crushed cookies. Pour the cream cheese mixture over the crust.
Bake at 350°F for 10 minutes. Lower the temperature to 200°F and bake for 1 hour and 10 minutes or till the center no longer looks wet or shiny. Remove the cake from the oven and run a knife around the inside edge of the pan. Chill, uncovered, overnight.
TO MAKE THE CHOCOLATE GLAZE: In a small saucepan melt chocolate chips and shortening over low heat, stirring constantly. Spread warm chocolate mixture over cheesecake. Garnish with shaved white chocolate. Chill till serving time. Makes 12 to 18 slices.