Oreo Cheesecake

This recipes is my aunt Janet's:

1 pkg. Oreo Cookies                                       1/4 cup butter or margarine

4 pkg. Cream Cheese (8 oz)                            1 cup sugar

1 tsp vanilla                                                     1 cup sour cream

4 eggs

Preheat oven to 325 degrees.  Place 30 cookies in food processor and process for 30 to 45 seconds, or until fully ground.  Add butter and mix well.  Press firmly into bottom of foil lined 13 by 9 baking pan.  Beat cream cheese, sugar and vanilla in a large bowl with electric mixer on medium speed until well blended.  Add sour cream and mix well.  Add eggs, one at a time, beating just until blended after each addition.  Chop remaining cookies.  Gently stir 1 1/2 cups of crumbled cookies into cream cheese batter.  Pour over crust, sprinkle with remaining crumbs.  Bake 45 minutes or until center is almost set.  Let cool.  Refrigerate 4 hours or overnight.  Cut into 16 pieces.  Store leftovers in refrigerator.