In a small bowl, mix crushed cookies and butter. Press onto bottom of a greased 9-in. springform pan. Refrigerate until ready to use., In a small saucepan, sprinkle gelatin over the cold water; let stand 1 minute. Heat and stir over low heat until gelatin is completely dissolved. Let stand 5 minutes., In a large bowl, beat cream cheese and sugar until smooth; gradually add milk. Beat in gelatin mixture. Fold in whipped topping and chopped cookies. Spoon over crust. , Refrigerate, covered, overnight. Loosen sides of cheesecake with a knife; remove rim from pan. If desired, garnish with additional chopped cookies.