Preheat oven to 425F. Butter bottom and sides of springform pan. Break cookies and put into food processor fitted w/ metal blade. Process til crumbs.
Add butter, mix til blended. Pour into pan; press evenly over bottom and 2/3 up sides. Refrigerate while preparing filling.
Filling:
Beat cream cheese in large bowl w/ electric mixer on medium until smooth. Scrape down sides. Add 1.25 cups sugar, beating until lite & fluffy, about 3 minutes, scraping down occasionally.
Mix in flour. While beating continuously, add eggs & yolks; mix until smooth. Beat in cream and 1 t. vanilla til well blended.
Pour 1/2 the batter into prepared crust. Sprinkle with chopped Oreos. Pour remaining batter over; smooth with spatula. Some oreos may rise to the top.
Put pan on baking sheet. Bake in 425F oven 15 minutes. Reduce oven temp to 225F and bake for additional 50 minutes or until set.
Topping:
Remove cake from oven & increase temp to 350F. Stir together sour cream, vanilla, and sugar. Spread mixture evenly over cake top. Return to 350F oven and bake 7 minutes or til topping begins to set. Remove from oven; cool in draft-free place to room temp. Cover & refrigerate several hours or overnight.
Can be refrigerated up to 3 days (if it lasts that long). Before serving, remove sides of springform.
