2 2/3  cups          chocolate sandwich cookie crumbs
                        (about 28 cookies)
     1/3  cup           butter or margarine -- softened
   3      packages      cream cheese (8-ounces) -- softened
   1      can           sweetened condensed milk (14-ounce)
   3      large         eggs
   1      tablespoon    vanilla extract
  16                    chocolate sandwich cookies -- coarsely crumbled
   1 1/2  cups          sour cream
   2      tablespoons   sugar
     1/2  teaspoon      vanilla extract
Combine cookie crumbs and butter, stirring well.  Press firmly on bottom
and halfway up sides of a 9-inch 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 400 degrees for 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 1/2 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.