Preheat oven to 325° F for an 8-inch cake or to 350° F for a 9-inch cake.
In small bowl, combine crumbs, sugar and butter; blend well.
Butter sides of spring-form pan. Press crumb mixture into bottom of pan.
In a large bowl, beat cream cheese with an electric beater until light. Gradually add the sugar. Add egg yolks one at a time, beating well after each addition. Stir in 1/2 of the vanilla extract.
Beat egg whites until stiff peaks form in a medium-size bowl. Very gently fold egg whites into cream cheese mixture. Pour mixture over crumbs. Bake until set and lightly browned on top. Bake an 8-inch cake for 30 to 35 minutes. Bake a 9-inch cake for 1 hour. Let cake cool on wire rack for 15 minutes.
Turn oven up to 400° F.
Blend sour cream, and remaining sugar and the remaining vanilla extract in a medium-size bowl. Gently spread over top of cheesecake and bake until set, 5 to 7 minutes for an 8-inch cake or 10 minutes for a 9-inch cake. Cool to room temperature on wire rack. Chill at least 4 hours in the refrigerator.Makes 4 Source: