Combine cookie crumbs and butter, stirring well. Press firmly on bottom and halfway up sides of a 23 cm springform pan. Chill.

Beat cream cheese until fluffy in a large mixing bowl; gradually add sweetened condensed milk, beating until smooth. Stir in eggs, mixing well. Add 1 tablespoon vanilla. Fold crumbled cookies into cream cheese mixture. Pour into prepared pan. Bake at 200ºC or 5 minutes; reduce oven temperature to 325 degrees and continue baking 55 to 60 minutes. (Top will be set and center may be soft but will become firm when chilled.) Combine sour cream, sugar, and remaining half teaspoon vanilla; stir well. Gently spoon sour cream mixture evenly over cheesecake, and spread evenly to edges of pan. Bake an additional 10 minutes. Cool to room temperature; cover and chill overnight.