Prepare crumb crust by combining crumbs, butter and 2 tablespoons sugar. Press mixture into bottom and up the sides of a 23cm springform tin. Refrigerate. Meanwhile, preheat oven to 180 degrees C.
Melt white chocolate chips in top of a double boiler over hot water, or in the microwave. Set aside.
Beat cream cheese and 1 cup sugar in a large mixing bowl until smooth and creamy. Blend in eggs. Gradually pour in chocolate mixture beating on low speed until well-blended. Add 1/2 cup sour cream, flour and vanilla. Blend until smooth. Pour into prepared crust.
Bake for 55 - 60 minutes or until filling is firm. Turn oven off. Cool cheesecake 1 hour without opening door. Remove and let cool completely. Chill ovenrnight before serving.